Thanks for the info Waynel!
I'm wondering if anyone has done it in a VW Touareg. It can't be that much different from an Audi.
I see you used the AC control to connect to the CAN bus. In some cars you can use the OBD2 plug to also connect to the can bus (http://www.intrepidcs.com/vcan/vcanobd.htm). have you tried connecting the can adaptor to your Audi A4's OBD2 plug PIN6 and PIN14 (as seen on the link above)?