Will the sensor be mounted in a fixed location or will it still move with the operator -- just not mounted directly on the HMD?
If the former, you should be able to detach the LeapHandController from the camera and place it in the location of your scene corresponding to the placement of the physical Leap Motion control. Make sure the "Is Head Mounted" mode is switched off.
If the later, you would offset and rotate the LeapHandController to correspond with the offset of the physical device from the center point of user's inter pupillary line segment (the midpoint between their eyes). You would have to experiment whether turning "Is Head Mounted" is better or worse in this setup.