(no Audi content) Adding input to CD changer controller?

["Rob Andrews" <rob@smu.edu>]

I'd like to be able to add an input to my CD changer, i.e. run whatever
audio output I'd like (I want to design an mpeg player for the A4) to the CD
changer input.  I have a Kenwood head unit.  I figured this would be the
best way to get the greatest sound quality.  Anyone know how I would go
about doing this and what wires I need to tap into, if this is possible,
general info, etc.?  Thanks!
Rob