The form factor hasn't really changed from the ice iBook G3 (Dual USB). They're actually pretty easy to take apart. The case basically snaps together after you remove a couple of screws. The hardest part is remembering where all the screws go back. Apple uses about 15 different screws, sizes, and lengths.
Just remember, that when you do this, you can kiss your warranty good bye, even if you've purchased the AppleCare Extended Warranty.