This great article explains how to implement scripts in SCOM.
There is not a lot of documentation for System Center Operations Manager 2007 yet.
It is coming, but there's a lot of things that changed since the previous release and I think some more would only help. Also, a lot of the content I am seeing is either too newbie-oriented or too developer-oriented, for some reason.
I have not yet seen a tutorial, webcast or anything that explains how to create a simple unit monitor that uses a VBS script using the GUI.
So this is how you do it: