Add a PowerShell Provider without Import-Module

Import-PSProvider.ps1

using namespace System.Management.Automation
using namespace System.Management.Automation.Provider
using namespace System.Management.Automation.Runspaces

[CmdletProvider('MyProvider', [ProviderCapabilities]::None)]
class Provider : DriveCmdletProvider {
    [PSDriveInfo] NewDrive( [PSDriveInfo]$drive )
    {
        return ([DriveCmdletProvider]$this).NewDrive($drive)
    }
}

function Import-PSProvider {
    param(
        [String]$Name,
        
        [Type]$Type
    )

    $sessionStateProviderEntry = New-Object SessionStateProviderEntry(
        $Name,
        $Type,
        $null
    )

    # System.Management.Automation.Runspaces.LocalPipeline will let us get at ExecutionContext.
    # Note: $ExecutionContext is *not* an instance of this object.
    $type = [PowerShell].Assembly.GetType('System.Management.Automation.Runspaces.LocalPipeline')
    $method = $type.GetMethod(
        'GetExecutionContextFromTLS',
        [Reflection.BindingFlags]'Static,NonPublic')
    # Invoke the method to get an instance of ExecutionContext.
    $context = $method.Invoke($null, [Reflection.BindingFlags]'Static,NonPublic', $null, $null, (Get-Culture))

    # Get the SessionStateInternal type
    $type = [PowerShell].Assembly.GetType('System.Management.Automation.SessionStateInternal')
    # Get a valid constructor which accepts a param of type ExecutionContext
    $constructor = $type.GetConstructor(
        [Reflection.BindingFlags]'Instance,NonPublic',
        $null,
        $context.GetType(),
        $null)
    # Get the SessionStateInternal for this execution context
    $sessionStateInternal = $constructor.Invoke($context)

    # This attempts to verify that we have the "right" session state
    # $currentLocation = $type.GetProperty('CurrentLocation', [Reflection.BindingFlags]'Instance,NonPublic')
    # $currentLocation.GetValue($sessionStateInternal)

    # Get the method which allows Providers to be added to the session
    $method = $type.GetMethod(
        'AddSessionStateEntry', 
        [Reflection.BindingFlags]'Instance,NonPublic',
        $null,
        $sessionStateProviderEntry.GetType(),
        $null)
    # Invoke the method.
    $method.Invoke($sessionStateInternal, $sessionStateProviderEntry)
}