Right then, just done this to mine this morning, although its a 95 model, I guess they are the same or at least v similar...
There should be 6 screws in total holding the control fascia on, 2 behind the ashtray, and 4 behind the control fascia cover.
Remove all the screws then remove the lower section of the fascia (the one with the heated rear screen switch in)
You can then tease the control mechanism out of the dash to reveal a white shroud type thing around the centre knob. I had to tip the mechanism to the side then out through the gap.
WARNING - the control mechanism will only come out a little way, dont force it, you'll break something!
It will come out enough to get access to the white shroud, and therefore the bulb within it.
Unplug the wiring connector from the back of the white shroud, and pop the shroud off from the mechanism. You should then see a green plastic bit with the bulb inside it. You have to remove the green bit, then the bulb will pull out.
Its a 12V 1.2W bulb BTW