I've done the same, I found that there is a data line from the Airbag ECU that talks to the UCH,
The Airbag ECU is feed with battery voltage at key on and if there is no comms with it the light stay's on (Doing it's job i suppose)
I tried refitting the airbag Ecu and adding resistors, The only problem i had while doing this was fooling the ECU that the sill crash sensors where still in circuit. ( Don't think you can resistor these ).
So i'm back to square one.
I'd be very interested how Burp did it..... I'm ready for desoldering the airbag and service lights out of my dash.