http://www.rennteam.com/showflat.php?Cat=&Number=37202&page=1&view=collapsed&sb=5&o=93&fpart=1

http://www.rennteam.com/showflat.php?Cat=&Number=35577&page=1&view=collapsed&sb=5&o=93&fpart=1

You might want to check these out. Solutions for ipod to car radio conections have been discussed in the cayenne board.

Hope you find a solution that fits your need.

Ricardo.