i tried to do the plyo program outlined here, but it as way too ambitious for me:
http://www.pponline.co.uk/encyc/0879.htm

so i just gave up on working on it on my own. what we do in class is things like tuck jumps, bringing your knees as high as possible; jumps with your legs straight, just bouncing off your toes, but not really bending and flexing your ankles much either (i don't really understand these...); and jumping forward and then back as far as possible.