Your Powerbook should have come with a s-video to RCA dongle. Use this to connect to the TV video in port (yellow) with a standard RCA cable. A better option if your TV can do it would be to get an S-video cable and connect it to the TV's S-Video port. This is better because it elimates the easily lost dongle.
Once you hook the cable into the TV, select the proper channel/video in setting on TV and then hit Detect Displays on your mac.
I connect my TV at home this way all the time. The quality is not as good as an external monitor, but it is perfectly fine for doing a slide show or watching a movie, etc.