A8 ABZ immobilisation system - for electro-geeks:)

Hello everybody.
I've bought quite fine ABZ with wiring and ECU. I want to put it to quite different car, than donor-A8. And my problem is to overcome immobilisating system, which normally uses some of 3 wires from ECU to instument cluster, and one - to communicate directly with immo module.
Will be grateful for any advices, how to do it. See two ways - to "fake" an ECU, giving to it some signals simulating unlocked immo (ground signal or +5V or +12 ????), or re-programming ECU.
I'm interested in more simple solution, of course, I don't like to make additional problems for myself.

Thanks for all
Sebastian