It must be similar to a 156................get an old 8v though, no airbags
disconnect battery for 20-30mins, then unscrew the 3 allen/hex head bolts behind the wheel, which holds the centre hornpush/airbag unit in place.(you'll be able to feel behind the wheel, roughly where each spoke is, that there is a hole behind it) I think they are 5mm hex bolts if I remember correctly. Once these are undone, carefully lift out the airbag horn unit, but do not force it out, as the airbag connector is still attached to it, turn it around enough so you can get to the connector, then with a small tipped precision flat head screwdriver, lift the centre little tap that is holding the connector/plug in place, once that is removed you can unplug the connector from the airbag unit, and put it to one side.
Next, you'll see a black circular plastic cover in the middle of your wheel, this a protective cap that covers the captive nut which holds the steering wheel. This cap has to be removed, best way I found was using the short head of an allen key, placing it behind the lip, and pulling/wedging it up. Do this at more that one side of it, and with a little play it'll come off. Once the cap is removed, it will expose the main nut. Now although this looks a like a strange caged nut, do not be fooled or alarmed, it is removed just like a regular nut using a socket and ratchet, the size is 24mm. Once this is removed, make sure the wheel is still aligned straight. Before you start pulling the wheel off you also have to disconnect a black connector/plug, on the left hand side of the wheel, the cable leads out to same point/whole where the airbag cable feeds off too. Once this is unplugged you can now begin to attempt to remove the wheel! Best method I have found, is to gently, but firmly tilt the wheel side to side, whilst pulling on the wheel gently. Do NOT however yank the wheel aggresively, as if and when it does come off, you can rip the airbag and black connectors wiring right off , once the wheel has come off the shaft, feed the connectors individually, through the whole on the wheel, freeing the steering wheel! And thats it!