I've never been successful in removing broken pins from these DC-in ports but I've had a few colleagues who have removed these before, though it's always been more of a luck thing.
I would recommend removing the battery and then trying to grasp the pin with some small, thin tipped, but sturdy tweezers or pliers. You might magnetize the tool you're using to grasp to add a little more help.
In all of the scenarios I've attempted I have always ended up replacing the DC-in board due to failure. It's a relatively straight forward repair so long as you keep track of screws & follow each step. You didn't specify the exact model iBook but the procedure is pretty similar for each of the G4 iBooks.
12" 1.33Ghz G4 iBook DC-in board replacement
The part itself is usually fairly cheap as well, in the $20-45 range.