The sensor that comes with the aimtrak guns connects with usb and is about 5 inches wide. it has a 4 ft cable, so not very long. They say the sensor needs to be on top so your millage may vary. I would contact them to see about putting it below the screen. what I mean by level is the the sensor par itself is level so the light guns can get a good straight line of sight with it.
hope this helps