Here is the deal. I am yet to do this but this is what came back to me from the post.
I am not sure how to deactivate the airbag either.
You will need a long T25 torx bit to remove the airbag, then a 10mm 'allan key' socket to remove the steering wheel.
Remove the steering angle sensor with a small phillips head screwdriver but first ensure that the steering is straight.
Then remove the combi switch and cruise control switch by removing the screws and then sliding forward the stalks.
Drop the under dash panel to access the wiring, disconnect and feed the wiring on the new switch through.
Should take half an hour, you may need a hand to get the steering wheel bolt undone, remember to do it up tight. Probably an idea to dissasemble first to ascertain whether it is actually broken rather than simply dislodged before buying the parts.