I am doing the same thing basically, but instead of CPwizard, I am using Mamehooker to show an image. I still am in the first phases and I haven't got my instruction cards made up yet for the games, but it automatically displays a JPG file that is named after the mame rom name. It pretty much did this out of the box with very minor fiddling. If you still have issues with CPWizard you might give Mamehooker a try.
Edit.. Just saw that you wanted the control panel info and game info controls. I am not aware of a way to toggle two images in mamehooker, but someone else might know. Good looking panel by the way, I like it..