Maybe this can work by having two computers, each with two kinects, capturing at the same time.
Then, with a video editing software, you stitch up the two dual captures, side by side, synchronized.

This could be useful for extending the capture area and/or reducing capture focal length distortion.
In any case, "iPi Desktop Motion Capture" would have to be coded to accept any amount of kinects.

I hate to cast aspersions...

But Im thinking this is just a photoshop job, and no such tools actually exist.

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Yeah, this definitely seems like a scam. Guy is asking people to send him Kinects, asking for free copies of iPi. Definitely not legit. I'm having issues with the IR light from TWO kinects clashing. Can't imagine how 4 Kinects could possibly function without interference.

Either way, I would not trust this person.

It appears you can indeed "fake" a four kinect capture by stitching up two synced dual capture videos.
However i was unable to find an avi file format that would be supported as 'depth video' inside of iPi...

To be continued!

I was about to suggest doing something like this after working with the dual set up kinects.
It would be easy to do. coming from a motion-control VFX back ground working with multiple takes on robotic repeating camera heads what we would do is lock the units to timecode and a clapper board that hits and starts on a certain TC frame.

What you could easily do here is use 4 or more kinects, providing they can all see a single point in the capture space easily (which they would have to anyway) and use a single "bloop" light or LED based light on a switch. Turn it on and off and thats your start frame for all the kinects to be locked to when you are lining the video results back up.
You would use as many machines as you needed to make your set up work and hit record on all of them (2 kinects per computer so 2 computers for a 4 kinect set up, or 3 for 6 kinect set up), then position your bloop light and "fire it", walk out, get character actor in there, proceed, then do the "tail bloop" light fire at the end of your shot and there you go, now it can be easily lined up in just about any edit tool.
The real question is, can ipisoft even handle that and what way would it expect the video to be formated, horizontally, quad views?