One such photo-journal (for older 400/500 MHz models): http://homepage.mac.com/sysop/PhotoAlbum13.html
Another one, aimed towards hinge repair (also for older TiBooks):
http://www.mcj.de/MAIN_PowerBookG4hinge.html
And for mine, the Powerbook G4 (DVI) Take Apart / Service Manual
And if I screw things up, here’s a place to buy a replacement logic board