Don and I discussed this a few years ago. Since that time HD prices have fallen and the drives have gotten much bigger. It is certainly now feasible to scan the pages of all your fake books (why bother creating digital copies of the music; e.g., cakewalk) and save them. With the 6 or 8 gig capacity of the PSR-9000 HD it would be nice if you could store them there and somehow use the video output to put a scanned page up on a TV set for viewing (you could freeze the TV picture with "freeze frame" that some sets have) while you switched the synth back to other musical HD functions. But all that is quite complex. Easiest to just do the scans and put them into a notebook computer.
Bob