Cool! Thanks for your reply... I'll look into it furtherThere are several pre-loaded images that can be accessed via the diagnostic interface, but after you set one, it will revert to the old image the next time the car starts. The only way to change it "permanently" is to change the AS-BUILT data, using OBD-II and FORSCAN, though you're limited to what is pre-loaded.
To see what's pre-loaded, hold down the Right Seek and Eject button when on the Audio screen in Sync 3, hit End Test, then navigate the menus to see what there is. I can't remember which submenu has the background images.
JR