I don't know about compatibility beyond LH cars. Intrepid, 300, and Concorde RKE modules from 02 to 04 should match up. The RKE module is fairly easy to find online or in a junkyard, but finding one WITH it's corresponding key fob isn't.
Without a key fob that is already programmed to that module, you'll have to have it done at the dealership.
On the other hand, you can order a new one from MOPAR, with 2 programmed remotes for about $80-90.
I was actually planning to add RKE to mine last weekend, but the pull-it-yourself junkyards here ALMOST NEVER keep the keys or key fobs once the cars are "planted". I may have to settle for new.