Don't waste your money on this link - the claim of "dealer programming" in that ad is an out and out lie. Go with the link to Piland.
When my factory remote died, I did a bit of research on it, and even downloaded the data sheet for the microchip inside it. This is what I learned:
It is an IR (infrared) remote; it works like a TV remote - line of sight. It
cannot be reprogrammed at the dealer, though it is the factory part. The microchip inside it puts out a series of pulses through the IR emitter. The exact sequence of pulses is determined by a number of input pins (12, I think) on the chip, which can be wired to one of three states - high, low, or float (no conection). That means there are a huge number of possible combinations. The receiver and transmitter use the same chip, and must be wired identically for the remote to work. Inside the remote and on the receiver circuit board you can find a little sticker with a 5-digit code. Only if the transmitter and receiver have the same code will the remote work the locks. Exactly how that code number is translated into the correct combination of highs, lows, and floats is not widely known.
Having been inside the factory remote, I can tell you that the microchip in question is a tiny surface-mount device. My guess is that you cannot change a remote's code by resoldering the pins (even if you had the skills) because the actual connections are etched into the layers of the circuit board itself.
For an XJ with the IR keyless system, there are only two real options - buy from Piland or replace it with an aftermarket system - if you want keyless access. The Piland unit is pysically more robust (mine's been in my pants pocket every day for nearly nine years now and has been dropped countless times, and still works fine) than the OEM. I'd recommend Piland to anyone looking for a remote for the Jeep IR keyless.
Rob