logjamelectronics.com can put an aux input into almost any factory stereo. The adaptor I have for my Toyota Tacoma allows me to set the CD changer to disc 1 / track 1, eject the CD, and listen to the aux. Put the CD back in and the CD plays. It was ~ $75 and took less than 15 minutes to install following radio removal instructions on the net.
Once you go direct, nothing else will do!