How to rotate iBook G4 display?

I have a 12” iBook G4 800mHz running Tiger and I need to figure out how to get it to display in portrait mode so that I can read sheet music from it.
Is there a terminal script or hack that will allow me do do this? And no, holding down the option key when opening Display Preferences doesn’t work. Or at least it doesn’t give me the option.

Thanks,