Go to your local locksmith. Most have the "box" to program a remote. I paid 20 bucks for 1 remote.
Dealership
You have to program it with a DRB (Scan tool).
I had the same problem. Google "keyless entry remote 2003 Jeep Grand Cherokee".
dealer has to do it with factory scan tool
If you have 2 (a pair) it tells you in owners manual to program the 3rd. If you are programming a second, you will have to goto dealer so they can program it with drb3.
Remote start was not available on a 1999 Jeep.
The only way to program keyless entry is with a very expensive diagnostic tool called "Launch" or go to nearest dealer for programming.
how do you program your remote
How do i program my remote car starter / lawless remote
The dealers scan tool is required.
It is easy to do with online instructions. Just google "2004 Jeep remote programming"
how to program remote for mini cooper