The directions are at
http://www.q45.org/remote.html but basically it's this: (copied from their website)
While sitting inside the vehicle:1. Open the trunk.2. Close and lock all doors.3. Insert and remove the key from the ignition six times within 10 seconds.4. Manually unlock and lock driver's door once to enable "setting" mode.5. Push lock button on the new remote controller once, just long enough to hear it beep, within 5 seconds of completing step 4.6. If additional remotes are needed (up to 3), repeat steps 4 and 5 for each additional remote immediately after programming the first remote. (Note: a total of four (4) remotes can be programmed to function on the same vehicle).