My steering wheel buttons were looking pretty worn, and thankfully you can now buy just the rubber buttons, without having to buy the whole silver bit as well. I got them from here: http://www.ebay.co.uk/itm/ALFA-ROMEO...IAAOSwubRXKk5s
They're basically identical to the original ones (Pic 1)
1) Start the engine and turn the steering wheel off-centre a little bit. This will make it easier to get at the allen bolts on the back of the wheel, without hitting the indicator and wiper controls.
2) Shut her off and disconnect the battery. Leave it for 15 mins or so.
3) On the back of the wheel there's three allen bolts holding in the airbag. They're pretty tight so have a little tube to slip on the end of your allen key for more leverage. They loosen off after a few turns, but don't come out.
4) Gently lift out the airbag. You could unclip the electrical connection but I just let it sit gently half in/out. It's probably best not to let it hang but the wire.
5) The silver things just pull out with a bit of force. If they're not moving then maybe gently lever them with a screwdriver. They're connected to a ribbon so be careful not to tug on it too hard. (Pic 2)
6) Flip it round and you'll see a black plastic piece clipped into the silver bit. There's two tabs at the top (Pic 3) that you need to bend back with a small flat head screwdriver. These can be pretty tight so be forceful but try not to snap anything. They'll click once they're released.
7) Separate the black and silver bits. The black bit will still be attached to the ribbon. The rubber buttons are sitting in the silver piece, so swap them with your new ones.
8) This is where I ran into a bit of trouble. With the new buttons in, the black bit wouldn't clip back into the silver piece anymore. I used a small file to enlarge the holes in the silver piece, to allow the little tabs to slide in easier. Press the black bit in hard, and you'll hear a click once it's secured.
9)Push the assembly back into the wheel. Make sure that the blue ribbon is nice and neat so you don't kink it when you put the airbag back in.
10) Repeat for the other side.
11) Put the airbag back in place, and tighten up the allen bolts.
Done! Looks much better!