Mp3 player or ipod connection

If you have a CD changer connected it is quite easy, if not I can't imagine a solution.
With a CD changer you need a cinch-Y-cable and a cinch-to-stereo jack adaptor. You connect these two to you ipod and the second port of the cinch-Y-cable to your CD changer.
Then you can burn a CD with no sound on it, but it must not be empty! You can use NERO Waveeditor to record "nothing" for the length of one CD and then burn this file.
If you play this CD in the CD changer and press the play button on your ipod you'll hear your itunes. If you play another CD in your CD changer while listening to your ipod you'll hear both sounds.

Have fun.