"Thumbs Up" to Ambesh, however I'd still question the requirement for such a script.
Why is allowing the client to update from the SEPM via the heartbeat not enough? Can you elaborate on your use case please?
A major benefit of updating via heartbeat this is that it allows the clients to update using delta files (which are faaaaaar smaller), minimising network load. The script provided by Zebellin doesn't do this, and neither does updating from a LUA (which would allow you to update with a simple script to call LUALL.exe or SepLiveUpdate.exe).