New GearVR Motion Controller
I just purchased the new controller for the GearVR that released a couple weeks back. In multiple places it claims it's a "motion tracking" controller, and there's a .position property from OVRInput, ...
Forum Discussion
There is a game I've just tested called Swords in Space which has directional tracking on the sword - you can move it left or right, or do figure eights with it. So it's definitely possible - might want to contact the developer of that game and see how they did it?