Disconnect the battery. Pull up the passenger side carpet and false wall, under the false wall you should see a grey cable with a red connector. It'll be the only red connector there, disconnect the red connector - be sure to grasp firmly by the sides and work it off DO NOT try to pull off the connector by the cable as the connector will break.
Using the appropriate sized torx or six point (or a 4mm hex in a pinch) loosen the two bolts that retain the air bag, they are accessed from the back side of the steering wheel. Ease the bag away from the wheel and disconnect the electrical connection on the back. WHen you disconnect the lead from the back of the airbag (should be a yellow or red connector [new part #124 XXX xx xx has yellow, 126 XXX XX XX has a red]), the explosive charge automatically shunts. When you reconnect you MUST HEAR IT CLICK AUDIBLY, that click unshunts the squib. Store the bag with the metal plate down while removing the wheel and cruise lever.
When I turned the key the first time after replacement of bag and sensor I sat in the passenger just in case.
Hope this helps.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.