So you want mouse wmulation with Pimax?
Here are Some ideas,
Airmouse and velcro,
IR leds and Trackir mouse mode.
Wiimote, velcro and glovepie/freepie mouse emulation,
Opentrack has alot of options for input devices and can emulate a mouse – including a program called Opentrackkinect which uses the kinect 360 or 2.0 as input and can output as a mouse
There are many tutorials online and a subreddit “DIYRIFT”
Which might interest you.