this is what i would do, if you have an external Hard Drive load OS X on it, boot into the xternal, then get a file recovery program such as Drive Genius, or Data Recovery 2. salvage what you can off the internal HD with those, copy them over to the external drive. shut down and remove your external drive, then boot up with your OS X dvd in again, and load OS X back on to your PowerBook.
i would do that if nobody else here has a way to bootback into OS X