Ipod Cd Changer Bus Connection

[jholmesuk]

Hi,
Ive just bought an Audi A4 TDI and it only has the concert cassette deck stereo in it, i am in two minds as to whether change the head unit or look for another method of connecting my ipod to it. I used to have a pioneer headunit in my last car and it was possible to connect a cable to the cd Changer bus socket which would let the head unit think there was a cd changer there. Effectively, turning the CD mode into an Aux mode. This was possible by simply connecting the CD bus sockets audio out L&R to a minijack to connect to the ipod. Is this possible on the Audi Concert series of Head units? Has anyone ever tried such a thing? If so, any advice would be great!!!!
Cheers

jholmesuk