We've been working to streamline our support for additional controllers, as we work to allow custom offsets per controller, for things such as adjusting the cheek weld on rifles.
The first fruit you'll find along the road, is support for one of the first offical Vive tracker accessories: the Hyperblaster.
It supports the pistol, with teleport or VRMoveMe (using 2 additonal trackers, and a vive controller) for locomotion currently.
Drop by the forums and let us know what you think :)
We have an xbox 360 Top shot Elite on the way to add support for that, as we've been told only the PS3 version was working, so once it comes we'll get support for it in asap.