Grant a role to a user on a Reporting Services item

RSPermission.ps1

$ReportServerUri = 'http://myreportserver/ReportServer/ReportService2005.asmx'
$InheritParent = $true
$ItemPath = '/SomeReportFolder'
$GroupUserName = 'MYDOMAIN\SomeUser'
$RoleName = 'SomeReportServerRoleToGrant'

$Proxy = New-WebServiceProxy -Uri $ReportServerUri -Namespace SSRS.ReportingService2005

$Policies = $Proxy.GetPolicies($ItemPath, [ref]$InheritParent)

$Policy = $Policies | 
    Where-Object { $_.GroupUserName -eq $GroupUserName } | 
    Select-Object -First 1
if (-not $Policy) {
    $Policy = New-Object -TypeName SSRS.ReportingService2005.Policy
    $Policy.GroupUserName = $GroupUserName
    $Policy.Roles = @()
    $Policies += $Policy
}

$Role = $Policy.Roles |
    Where-Object { $_.Name -eq $RoleName } |
    Select-Object -First 1
if (-not $Role) {
    $Role = New-Object -TypeName SSRS.ReportingService2005.Role
    $Role.Name = $RoleName
    $Policy.Roles += $Role
}

$Proxy.SetPolicies($ItemPath, $Policies)