Almost two years later, I'd be interested to know the outcome of @notchrischen's attempt.
I have just encountered the same problem, no spare PCIe slot to mount Vive's wireless VR card. Tethered, everything works fine, but wireless would be more convenient.
Another possibility would be to move the graphics card to an external enclosure and put the wireless card in the vacated slot. But an external enclosure is two or three hundred pounds, so I wouldn't want to get one just on spec. How well does a VR-capable graphics card work in that configuration? Would it have latency or bandwidth problems?
