It would probably be DO-ABLE, but it wouldn't work. You see, the white iBook G3 had a different case design, and with the different case design comes different cooling tunnels, different I/0 ports, etc. You see what I am saying? You could probably fit a custom motherboard in there though, if you were willing to go to the trouble. But to answer your question, I would give it a shot if you have an extra iBook G4 that you absolutely do not need. I wouldn't do something like that to my iBook G4, I would just keep it haha.