i know this isn't a cherokee but thought i would give you guys a shot still
in my 04 silverado i dont want to put an aftermarket deck in it.. dont care that much and never had good luck with aftermarket radio's staying in the truck... i was woundering if anyone knew a way to hook up an mp3 player without using an FM tuner or a tape adapter

 

You could try an in-line FM Modulator. They're better than the transmitters. Here's another.