a quick and dirty test of the codewheel and detector from the deskjet printer.
turns out that it can generate 7200 pulses per single revolution in quadrature, which should be sufficient to use for positioning without any gearing on a telescope's axis.
the quadrature decoder is using a picaxe microcontroller using finite state machine code.
http://www.youtube.com/watch?v=GdWUQ3rguUU
just need to build a housing assly with proper alignment of the detector and wheel.