Behind where the cassette goes there is a black plastic seal, gently pry it up. Then there is a metal snap ring, pry it up with a screwdriver. Then if you tap the nondrive side with a mallet it should all come apart. They basically press together.
I have a service document at home I could e-mail. I seem to remember there being a large preload ring behind the cassette body. The preload ring had notches in it's outer diameter. 2 or 3 small screws sat in the notch and held it in place.