Topic: Tired of captions, want to show 2 images.

Ok, here goes:

Tall order I'm sure, but I would like to modify the code so that instead of showing captions it displays another image (to correspond with the large image) in the place where a caption would ordinarily go.  I can create the gallery.xml file by hand to include the names of the images i would like to put there.  I don't need any fancy borders (mine are white borders on a white background with rounded edges).

Can anybody provide a roadmap for me to follow to get this done?  I don't necessarily need the actual code, but a strategy instead.  I have tried my hand at toying with the existing code but ran myself into a circle.