The guy from Driver4VR had a solution but I never got it working without glitches. He used cheap bluetooth remote controls which will be used as the buttons.
The idea is cool. Your hands are free and provide 6dof tracking and even tilt. Then when you grab a gun, you can grab the remote and you'll have a gun in your hand which you can shoot with. Drop the gun and you're just there with your hands and fingers all tracked perfectly.
I ordered my remotes from cheap chinese vendors so maybe that's why they didn't work consistently but when it did work the problem was solved.