I find myself needing to replace my airbag rotary switch, but need to find out how to remove the driver's airbag without the thing going bang!

Managed to find the part number on Dialogys, but my version has never allowed me to view the workshop manuals - don't know why! I have also PMd silencer51 on the subject because he has replaced many of these I believe. Does anyone have any detailed info on the subject? Any help would be greatly appreciated!!
BTW - my local stealer wont even give me a ballpark figure for the job, they want to do a diagnostic check on it first - £88.12 - and if they do the work they will deduct it from the total cost! What would that be then? I asked. I couldn't tell you, we will have to do the diagnostics first was the reply!!!!

Gobsmacked but any help would be great.
Regards
Rob