It's normally around a 3.9Ohm resistor.
When I did the Saxo I cut off the airbag connector and soldered this into its place:
http://www.maplin.co.uk/p/metal-film-06w-39-ohm-resistor-m3r9If you want to keep it a little bit more stock looking then don't cut the connector off, but try to wedge the legs of the resistor into the pins on the connector and make sure you insulate it (you don't want bare resistor metal accidentally earthing).
I have to be honest though - if you're still on standard seats and seatbelts I would be looking first of all to replace that steering wheel with a standard one with airbag. The only situation in which I'd recommend to remove the airbag is if you're using bucket seats and harnesses.