Undo the pinch bolt on each side of the lower yoke/triple clamp remove the two plugs at the top of each fork leg and using a suitable tool screw the fork tubes clockwise (when looking from the top)and the legs will wind out.
If you look in the technical notes on this site there is some useful info.
http://www.hitchcocksmotorcycles.com/pi ... o_1988.pdf
I'm not sure what is the suitable tool for the later bi-hex tubes, but I haven't got one so I presume I used a large allen key when I did mine.