Unlock car, wind windows down, disconnect battery, go have a cuppa and a Benson.
At least 15 mins later, look for the 2 or 3 small holes on the rear of the airbag unit. Poke in a slim screwdrive to disengage the clips and th 'bag should pop off. Thereks a possibility it is held on with Torx screws instead (I've never looked and moth methods are found on modern pugs).
Withdraw the airbag and unplug it. Place it somewhere safe, well away from any radio emissions.
Then undo the big nut on top of the column and place a steering wheel puller on it. If you've not got a puller, try yanking it off. However, if you do this place the nut back on a couple of turns to prevent you getting smacked in the fizzog, and be careful not to snap the splined end off the top of the column, as occasionally happens.
Remove COM unit, refit new one, replace wheel, bag and battery, and hook up to Planet for programming. Easy.
on mine there is a square hole at the rear of the wheel,when the wheels in the straight ahead position,insert a small screwdriver in the hole and push on the screwdriver and steering wheel at the same time,you'll get a little parp off the horn but nothing to worry about,as chopper says if your yanking the wheel off put the nut back on a few turns so you dont do the same as my son,who yanked the steering wheel off so violently he had the plug for the airbag off as well,caused some discussion about soldering it back on that,as chopper says tho i would let the car go to sleep before attempting any of this