Most of the answer was in my first post from Doug's site http://www.redmelon.net/tstme/roll/ (his codes a lot neater than mine).

I have used similar techniques myself before for creating pop up boxes etc and disjointed rollovers and its just a matter of finding out what works and what doesn't. Loading an image in the background and then one in the foreground seems to work quite well, but loading 2 background images in the same place doesn't seem to produce the desired effect.

Anyway hope its of some use.