Sorry, kind of an old post to revive, but this is possible now if you are using Road Runner. Check into BlueZX3's GPS Events plugin. It can trigger any event based on your GPS location, and direction of travel. For instance if you are exiting your community, you don't want to trigger the gate opener to open the gate on the entrance side.
This is exactly something that I am going to do when I get a new car and computer installed. I already took the gate opener apart, and wired a FB output to it to "push the button" on the gate opener. I also ran another set of leads to a small momentary button that can be pressed manually. Sorta a "manual override" so to speak