well the only way you can get a line in, is if you fool the unit into thinking you have a cd changer plugged in.

only then does it enable the audio input.
the only thing that might work is this:

http://www.crutchfield.com/S-rbWKO5g...0&I=023IPODBOX

but i am not 100% sure it would work.
the light blue plug looks correct, and i know that Blaupunkt and Becker use the same interface.
but too expensive to buy it and try it.
unless i find a place that has a money back guarantee.