Uses the SPWebConfigModifications class to deploy custom PageParserPath entries to web.config.

Add-PageParserPath.ps1

Add-PSSnapin Microsoft.SharePoint.PowerShell

function Add-PageParserPath
{
    [CmdletBinding()]
    param
    (
        [Parameter(Mandatory=$true,ValueFromPipeline=$true)][Microsoft.SharePoint.Administration.SPWebApplication]$WebApplication,
        [Parameter(Mandatory=$true)][string]$VirtualPath,
        [Parameter(Mandatory=$false)][bool]$AllowServerSideScript = $false,
        [Parameter(Mandatory=$false)][bool]$IncludeSubFolders     = $false,
        [Parameter(Mandatory=$false)][bool]$AllowUnsafeControls   = $false,
        [Parameter(Mandatory=$false)][switch]$WhatIf
    )
    
    begin
    {
        $modification = New-Object Microsoft.SharePoint.Administration.SPWebConfigModification -Property @{
                            Name     = "PageParserPath[@VirtualPath='$VirtualPath']"
                            Path     = "configuration/SharePoint/SafeMode/PageParserPaths"
                            Value    = "<PageParserPath VirtualPath=`"$VirtualPath`" CompilationMode=`"Always`" AllowServerSideScript=`"$AllowServerSideScript`" IncludeSubFolders=`"$IncludeSubFolders`" AllowUnsafeControls=`"$AllowUnsafeControls`" />"
                            Sequence = 100
                            Owner    = "AllowServerSideScriptPageParserPath: $VirtualPath"
                            Type     = [Microsoft.SharePoint.Administration.SPWebConfigModification+SPWebConfigModificationType]::EnsureChildNode
                        }
    }
    process
    {
        # basic validation

        # VirtualPath must start with a /
        if( $VirtualPath[0] -ne "/" )
        {
            throw New-Object ArgumentException("The VirtualPath value must start with a '/'")
        }

        # any wildcard reference must be the last character of the VirtualPath
        if( $VirtualPath.IndexOf("*") -ge 1 -and $VirtualPath.IndexOf("*") -ne $VirtualPath.Length-1 )
        {
            throw New-Object ArgumentException("An asterisk can only appear as the last character of the VirtualPath value")
        }

        $WebApplication | Remove-PageParserPath -VirtualPath $VirtualPath -WhatIf:$WhatIf.IsPresent

        if( $WhatIf )
        {
            Write-Output "Would have added new web config modification: $($modification.Value) to $($WebApplication.Url)"
        }
        else
        {
            Write-Verbose "Saving new modification: $($modification.Value) to $($WebApplication.Url)"

            $WebApplication.WebConfigModifications.Add($modification)
            $WebApplication.Update()
            $WebApplication.WebService.ApplyWebConfigModifications()
        }
    }
    end
    {
    }
}

function Remove-PageParserPath
{
    [CmdletBinding()]
    param
    (
        [Parameter(Mandatory=$true,ValueFromPipeline=$true)][Microsoft.SharePoint.Administration.SPWebApplication]$WebApplication,
        [Parameter(Mandatory=$true)][string]$VirtualPath,
        [Parameter(Mandatory=$false)][switch]$WhatIf
    )
    
    begin
    {
    }
    process
    {
        $update = $false

        for( $i = $WebApplication.WebConfigModifications.Count-1; $i -ge 0; $i-- )
        {
            try
            {
                $existingVirtualPathXml = [xml]$WebApplication.WebConfigModifications[$i].Value

                if( $existingVirtualPathXml.PageParserPath | ? VirtualPath -eq $VirtualPath )
                {
                    if( $WhatIf.IsPresent )
                    {
                        Write-Output "Would have removed existing modification $($WebApplication.WebConfigModifications[$i].Value)"
                    }
                    else
                    {
                        Write-Verbose "Removing existing modification $($WebApplication.WebConfigModifications[$i].Value)"

                        $WebApplication.WebConfigModifications.Remove($WebApplication.WebConfigModifications[$i]) | Out-Null
                        $update = $true
                    }
                }            
            }
            catch
            {
                # Write-Error $_
            }

            if( $update )
            {
                $WebApplication.Update()
                $WebApplication.WebService.ApplyWebConfigModifications()
            }

        }
    }
    end
    {
    }
}


# list existing WebConfigModifications
# Get-SPWebApplication | SELECT -ExpandProperty WebConfigModifications

# example how to deploy a new PageParserPath VirtualPath
Get-SPWebApplication | Add-PageParserPath -VirtualPath "/sites/finance/custompage.aspx" -AllowServerSideScript $true -IncludeSubFolders $true -AllowUnsafeControls $false -Verbose -WhatIf

# example how to retract any previously added (via SPWebConfigModifications) PageParserPath entries 
Get-SPWebApplication | Remove-PageParserPath -VirtualPath "/sites/finance/custompage.aspx" -Verbose

Update-DirectFileDependenciesAttribute.ps1

Add-PSSnapin Microsoft.SharePoint.PowerShell

function Update-DirectFileDependenciesAttribute
{
    [CmdletBinding()]
    param
    (
        [Parameter(Mandatory=$true,ValueFromPipeline=$true)][Microsoft.SharePoint.Administration.SPWebApplication]$WebApplication,
        [Parameter(Mandatory=$true)][ValidateRange(10,50)][int]$DirectFileDependenciesValue,
        [Parameter(Mandatory=$false)][switch]$WhatIf
    )
    
    begin
    {
        $owner = "DirectFileDependencies=`"$DirectFileDependenciesValue`""

        $modification = New-Object Microsoft.SharePoint.Administration.SPWebConfigModification -Property @{
                            Name     = "DirectFileDependencies"
                            Path     = "configuration/SharePoint/SafeMode"
                            Value    = $DirectFileDependenciesValue
                            Sequence = 101
                            Owner    = $owner
                            Type     = [Microsoft.SharePoint.Administration.SPWebConfigModification+SPWebConfigModificationType]::EnsureAttribute
                        }
    }
    process
    {
        $WebApplication | Remove-DirectFileDependenciesAttribute -DirectFileDependenciesValue $DirectFileDependenciesValue -WhatIf:$WhatIf.IsPresent

        if( $WhatIf )
        {
            Write-Output "Would have added new web config modification: $owner to $($WebApplication.Url)"
        }
        else
        {
            Write-Verbose "Saving new modification: $owner to $($WebApplication.Url)"

            $WebApplication.WebConfigModifications.Add($modification)
            $WebApplication.Update()
            $WebApplication.WebService.ApplyWebConfigModifications()
        }
    }
    end
    {
    }
}

function Remove-DirectFileDependenciesAttribute
{
    [CmdletBinding()]
    param
    (
        [Parameter(Mandatory=$true,ValueFromPipeline=$true)][Microsoft.SharePoint.Administration.SPWebApplication]$WebApplication,
        [Parameter(Mandatory=$true)][ValidateRange(10,50)][int]$DirectFileDependenciesValue,
        [Parameter(Mandatory=$false)][switch]$WhatIf
    )
    
    begin
    {
        $owner = "DirectFileDependencies=`"$DirectFileDependenciesValue`""
    }
    process
    {
        $update = $false

        for( $i = $WebApplication.WebConfigModifications.Count-1; $i -ge 0; $i-- )
        {
            try
            {
                if( $WebApplication.WebConfigModifications[$i].Owner -match "^DirectFileDependencies=" )
                {
                    if( $WhatIf.IsPresent )
                    {
                        Write-Output "Would have removed existing modification $($WebApplication.WebConfigModifications[$i].Owner)"
                    }
                    else
                    {
                        Write-Verbose "Removing existing modification: $($WebApplication.WebConfigModifications[$i].Owner)"

                        $WebApplication.WebConfigModifications.Remove($WebApplication.WebConfigModifications[$i]) | Out-Null
                        $update = $true
                    }
                }            
            }
            catch
            {
                # Write-Error $_
            }

            if( $update )
            {
                $WebApplication.Update()
                $WebApplication.WebService.ApplyWebConfigModifications()

                $stopwatch = [System.Diagnostics.Stopwatch]::StartNew()

                while( $stopwatch.Elapsed.TotalMinutes -le 5 -and (Get-SPTimerjob -Identity "job-webconfig-modification" -Verbose:$false) )
                {
                    Write-Verbose "Waiting for timer job to remove existing Web Config Modifications from all servers."
                    Start-Sleep -Seconds 5
                }
            }

        }
    }
    end
    {
    }
}


# list existing WebConfigModifications
# Get-SPWebApplication | SELECT -ExpandProperty WebConfigModifications

# example how to deploy a new DirectFileDependencies Attribute value.  Default is 10
Get-SPWebApplication | Update-DirectFileDependenciesAttribute -DirectFileDependenciesValue 20 -Verbose -WhatIf


# example how to retract the updated DirectFileDependencies Attribute value and return the default of 10
Get-SPWebApplication | Remove-DirectFileDependenciesAttribute -DirectFileDependenciesValue 20 -Verbose -WhatIf

Update-SafeControlMaxControlValue.ps1

Add-PSSnapin Microsoft.SharePoint.PowerShell

function Update-SafeControlMaxControlValue
{
    [CmdletBinding()]
    param
    (
        [Parameter(Mandatory=$true,ValueFromPipeline=$true)][Microsoft.SharePoint.Administration.SPWebApplication]$WebApplication,
        [Parameter(Mandatory=$true)][ValidateRange(200,1000)][int]$MaxControlsValue,
        [Parameter(Mandatory=$false)][switch]$WhatIf
    )
    
    begin
    {
        $owner = "MaxControls=`"$MaxControlsValue`""

        $modification = New-Object Microsoft.SharePoint.Administration.SPWebConfigModification -Property @{
                            Name     = "MaxControls"
                            Path     = "configuration/SharePoint/SafeMode"
                            Value    = $MaxControlsValue
                            Sequence = 201
                            Owner    = $owner
                            Type     = [Microsoft.SharePoint.Administration.SPWebConfigModification+SPWebConfigModificationType]::EnsureAttribute
                        }
    }
    process
    {
        if( $WhatIf )
        {
            $WebApplication | Remove-SafeControlMaxControlValue -WhatIf
            
            Write-Output "Would have added new web config modification: $owner to $($WebApplication.Url)"
        }
        else
        {
            $WebApplication | Remove-SafeControlMaxControlValue

            Write-Verbose "Saving new modification: $owner to $($WebApplication.Url)"

            $WebApplication.WebConfigModifications.Add($modification)
            $WebApplication.Update()
            $WebApplication.WebService.ApplyWebConfigModifications()
        }
    }
    end
    {
    }
}

function Remove-SafeControlMaxControlValue
{
    [CmdletBinding()]
    param
    (
        [Parameter(Mandatory=$true,ValueFromPipeline=$true)][Microsoft.SharePoint.Administration.SPWebApplication]$WebApplication,
        [Parameter(Mandatory=$false)][switch]$WhatIf
    )
    
    begin
    {
    }
    process
    {
        $update = $false

        for( $i = $WebApplication.WebConfigModifications.Count-1; $i -ge 0; $i-- )
        {
            try
            {
                if( $WebApplication.WebConfigModifications[$i].Owner -match "^MaxControls=" )
                {
                    if( $WhatIf.IsPresent )
                    {
                        Write-Output "Would have removed existing modification $($WebApplication.WebConfigModifications[$i].Owner)"
                    }
                    else
                    {
                        Write-Verbose "Removing existing modification: $($WebApplication.WebConfigModifications[$i].Owner)"

                        $WebApplication.WebConfigModifications.Remove($WebApplication.WebConfigModifications[$i]) | Out-Null
                        $update = $true
                    }
                }            
            }
            catch
            {
                Write-Error $_
            }

            if( $update )
            {
                $WebApplication.Update()
                $WebApplication.WebService.ApplyWebConfigModifications()

                $stopwatch = [System.Diagnostics.Stopwatch]::StartNew()

                while( $stopwatch.Elapsed.TotalMinutes -le 5 -and (Get-SPTimerjob -Identity "job-webconfig-modification" -Verbose:$false) )
                {
                    Write-Verbose "Waiting for timer job to remove existing Web Config Modifications from all servers."
                    Start-Sleep -Seconds 5
                }
            }
        }
    }
    end
    {
    }
}


# list existing WebConfigModifications
# Get-SPWebApplication | SELECT -ExpandProperty WebConfigModifications

# example how to deploy a new MaxControls Attribute value.  Default is 200
Get-SPWebApplication | Update-SafeControlMaxControlValue -MaxControlsValue 400 -Verbose #-WhatIf

# example how to retract the updated MaxControls Attribute value and return the default of 200
# Get-SPWebApplication | Remove-SafeControlMaxControlValue -Verbose -WhatIf