It depends on the forks. My Skyteam 200 had a very simple (i.e. cheap/primitive ) design. It was basically one long spring with an oil valve damper at the bottom. I simply unbolted the caps and cut a couple of inches off the springs. Other forks are more complicated. Heres a tutorial for a more sophisticated fork design.
http://www.customfighters.com/forums...ad.php?t=45166