There are a number of generic digital FM Modulators out there that will allow you to attach any line level device and play over an unused FM preset. Sound quality is more than sufficient for an MP3 or equivalent and they only run about $20 - $30 and are about the size of a large pager. Our VX antenna cable socket is actually near the steering column, so you could mount one behind the facia between the column and center dash.

Easy and simple!