I talked to Frank at Car Toys about this a couple of weeks ago. He has an adaptor that plugs into the head unit and a IPOD and your Sony remotes will still operate the head unit. Very trick set up. I think it was about $160.00.
Do you have an external CD player? I think it plugs into the RCA jacks for the CD player. With an IPOD, you would never used your changer again.