This is what I would use. http://www.crutchfield.com/p_142FMMOD02/Scosche-FM-MOD02.html?tp=121&awkw=42674262265&awat=pla&awnw=g&awcr=15087687625&awdv=t
Seems pretty easy. I used to be quite proficient with car stereo, so I could help. You could also just put in another receiver with an auxiliary input.