Yes, it is actually not so easy to find it any more..
Try here:
http://www.bbastrodesigns.com/BBAstroDesigns.html, there you will find a link to the page that you really need:
http://www.bbastrodesigns.com/StepperSystem.html
http://www.aavbae.net/taller/bipolar/bipolar_mod.php
Also, we had many discussions about steppers here on forum.. try to search older posts in this section.