Maybe my brain is goffed from lack of sleep or something but I really didn't understand.
You need a script that will create an IMAGE mouseover? Like change one image to another or change the COLOR of the image (same thing bascially just the second image is a different color than the first)?
Or...Are you wanting a mouse over text effect that will bring up an image.
Have you tried typing in IMAGE MOUSE OVER GENERATOR in the search engines yet? That would be my first stop. There are tons of them out there that will supply the code.
I would gladly help, I'm just not SURE what you're looking for.