the best way to do this is to undo the 3 allen key screws that go across the front of the dash (the black bit) then u need to pry off the little plastic bits either side of the clock and there are 2 allen key screws in there. that will get the whole black dash bit off.
then the dials come out with 4 phillips headed screws that u will b able to c, 2 above the dials which face you, and 2 on the bottom which face up wards, then unplug the 3 plugs (1 big one on left, 1 red and 1 white on right, remembering which one goes on top!) the dials will then be free apart from the speedo cable, u need to reach underneath the dials and unclip the speedo, dont just pull as u will pull the cable apart, u need to push the white bit back freeing the cable and the dials will com straight out.
u will then be left with a hole and the speedo cable head staring right at you!
getting the dials back on it
A LOT more difficult as there is a nack to gettin the cable back into the dials... wat i did was line the dials up, then reach under with my right hand (palm up) and semi push the cable back in, then remove my hand and push down on the dials to make sure the cable is in. reconnect the plugs, and take her for a little drive to make sure everythin is working, then just screw the dials back in, and re attach the dash with the allen key screws!
hope that wasnt too long winded!
p.s: i have snapped mine and was wondering how easy it was to change???
HTH
mase