From what I can work out, the future control for the Intel RealSense on the ST16 is the left hand button in the group of 3 at the top right of the controller. It's the only one "without a function" in the manual, and I believe it'll just be a push button "On/off". Clearly this will only come into operation when the module is fitted.
I could be wrong, but that's my guess!
I could be wrong, but that's my guess!