It sounds like the cable is just to re-join the wires that would normally have been linked by the airbag to complete the circuit, so the system doesn't notice the airbag is missing. The demon site suggests this will disable the whole airbag system though (not sure how).
Have you realised you're going to have to change the wheel back for the MOT each year though?
From April 2012 there are a couple of new checks on the airbags in the MOT
- firstly that the Airbag light comes on when you turn the key, then goes off as normal.
- secondly that there is an airbag fitted anywhere the one was originally fitted on the car.
So a non-airbag steering wheel would be an immediate MOT fail.