I use EZRain everyday in my irrigation setup and am looking into supporting that device as well.
I just saw the garage door relay the other day on Smarthome's website. I'm guessing that it acts like a relay switch and reports ON/OFF only. If you have the garage door relay in your Insteon setup try adding it to iLinc and select the SwitchLinc as the device. See if you can get the ON/OFF status of the garage door through iLinc. If that works, I'll just add the name to the device list.