I assume you mean this thread? http://www.mameworld.info/ubbthreads/showflat.php?Number=374374 If it's specifically about the backgrounds, there's not much to it. The background inlays (cardboard or plastic sheet) can be scanned after taking the handheld apart. Sean sends me the scan and I make a MAME .lay file for it. I align the background to the LCD segments in inkscape, and then use a script I made to create .lay coordinates and size.
