Elk makes a doorbell detector that 'should' work (I'm not familiar with the HAI though).
Do you currently have a doorbell? If so, and if you want to keep it, I would consider using a standard normally open door/window magnetic sensor, and place the sensor itself next to the coil that is used for the relay to trigger the 'dingers'. The magnetic flux generated from it should 'close' the sensor momentarily. HERE is the post on the HomeSeer boards where I got the idea showing how to place the sensor next to the coil.
Probably a good idea to use the Elk-960 to 'lengthen' the pulse to ensure the HAI unit picks it up. (So you would use the sensor to trigger the Elk-960, whose relay contacts would go to an HAI input). Problem with this method is the extra expense of the Elk-960 plus having to power it with 12 volts (but this shouldn't be an issue as you can mount this with the HAI unit in your wiring closet).
I currently use this method, but use a DS10a wireless X-10 sensor (just placed the sensor next to the coil, put batteries in the DS10a, and everything worked great).
Edited by BraveSirRobbin, 02 July 2013 - 07:51 AM.