A top secret powershell script to add paths to the system environment variables, hopefully.

AddSystemPaths.ps1

function AddSystemPaths([array] $PathsToAdd) {
 
  $VerifiedPathsToAdd = ""
 
  foreach ($Path in $PathsToAdd) {
    if ($Env:Path -like "*$Path*") {
      echo "  Path to $Path already added"
    }
    else {
      $VerifiedPathsToAdd += ";$Path";echo "  Path to $Path needs to be added"
    }
  }
 
  if ($VerifiedPathsToAdd -ne "") {
    echo "Adding paths: $VerifiedPathsToAdd"
    [System.Environment]::SetEnvironmentVariable("PATH", $Env:Path + "$VerifiedPathsToAdd","Machine")
    echo "Note: The new path does NOT take immediately in running processes. Only new processes will see new path."
  }
}

http://blogs.technet.com/b/sqlthoughts/archive/2008/12/12/powershell-function-to-add-system-path.aspx

http://www.mikepfeiffer.net/2010/06/how-to-add-functions-to-your-powershell-session/