The fastest way to do it is to write the PowerShell code yourself. Below is how the code will look in PowerShell, i would say that most C# developers should be able to grasp the concepts of converting C# code to PowerShell in a very short time.
Functions can be a little odd at the beginning, since the usual PS syntax is
myFunction Parameter1 Parameter2
Also you really should install PowerShell 3.0 and use the Windows PowerShell ISE tool to develop the code. Anyways it should not take you more than 1-2 hours to get your C# code running along in PowerShell.
[System.Reflection.Assembly]::LoadWithPartialName(”Microsoft.SharePoint”)
Write-Host "This tool will copy the users from one group to another group"
Write-Host "Please enter the URL of the site where your groups are available"
[string] $siteUrl = [Console]::ReadLine()
$site = new-object Microsoft.SharePoint.SPSite($siteUrl)
try
{
$web = $site.OpenWeb()
Write-Host "Please enter the name of the source group"
[string] $sourceGroupName = [Console]::ReadLine()
Write-Host "Please enter the name of the destination group"
[string] $destinationGroupName = [Console]::ReadLine()
$sourceUsers = $web.Groups[$sourceGroupName]
(and so on)
}
catch
{
Write-Error ("Failed to copy sharepoint users." + $_)
}