Sounds like you've got a bad optical drive. Bad timing to want to reinstall with a flaky drive. Go to
http://powerbookmedic.com/. They have drives as well as take apart manuals. They are generally no that hard to swap out unless its a 12' PB, then good luck to you because that's a complete take-apart including the logic board and inner frame!
You may be able to target disk mode another mac to the powerbook and install through the target disk mode macs optical drive.