Trying to do the same thing here.
Looking at using a Microsoft Wireless Display Adapter.(HDMI)
Then converting the VGA feed to the projector to a HDMI using a VGA to HDMI after market adapter. Then running a USB power lead to the Microsoft Wireless Display Adapter.
We also think we would need a VGA switch to save unplugging and re plugging all the cables back into each other.
I have not tested this as of yet but this should bridge the gap until all rooms have projectors with HDMI and USB ports.