Hi Mike.
I would like to help but i wouldn't know where to start..lol
Quite why Nige thinks i would know about Car phones is a mystery as i dont even know what SDS is !! I do have vagcom but i have to admit its one of those things i have not had time to get acquainted with as yet...it comes with no instructions so its a case of trawling the web.
If i was you i would go down to Bannings in walnut tree close where the guys are experts and fit this sort of stuff all the time, they helped me for free when i fitted my RNSE.
http://www.ianbannings.com/
sorry i cant be of more help
Paddy