This seems to be asked quite often, so from kb ..
How to use your Powerbook lid closed.
1. Connect a USB keyboard and mouse to your computer.
2. Close the computer's display to put the computer to sleep.
3. Connect the Apple VGA adapter that came with your computer to the VGA port on the external monitor or projector.
4. Connect the other end of the Apple VGA adapter to the video output port on the PowerBook G4 (12-inch) and PowerBook G4 (12-inch DVI) computer. (Or relative to other sizes of Powerbooks.)
5. Wait a few seconds and then press any key on the external keyboard to wake the computer.
Should be working now.
