I found this on another site. It still might work although it appears you still might need the dealer'* help:
ALL TRANSMITTERS MUST BE PRESENT WHEN PROGRAMMING NEW REMOTES!
1) Turn OFF ignition switch
2) Use a 3 amp fused jumper wire and connecte the terminal 8 (blk/wt) and terminal 4 (blk) wires at the data link connector. The data link connector is located on the drivers side bottom of dash panel
3) Close all the doors
4) Turn ON the ignition switch. The locks will cycle to LOCK
5) Press and hold LOCK and UNLOCK on one of the transmitters for 30 seconds.
6) After a 30 second delay the doors will LOCK and UNLOCK.
DO NOT TURN OFF THE IGNITION!
7) Repeat step 5 for each additional transmitter
Disconnect jumper wire from data link connector. Then turn ignition off and verify functions.
eBay is a good source for a replacement transmitter, but understand that they are NOT interchangeable. You must use the ONE that is meant for your car.