Do you have the make and model number ?
I have found (hard work 
) quite a few datasheets for steppers from old printers, maybe i have the one you need.
This site http://www.doc.ic.ac.uk/~ih/doc/stepper/
and here http://www.doc.ic.ac.uk/~ih/doc/stepper/control2/connect.html
has very good information on using stepper motors. It's focus is on controlling them with a PC's parallel port, but thats basically the same as using digital pins on the Aduino board.
MikMo
http://www.mkmo.dk