What if a few of us pitched in and put the money together? 10x$20 or 20x$10 should do it

That way, more of us share the risk
But then I'd feel bad if I couldn't get it to work.
A friend of mine has an 858 with the adapter. Next time I go shooting with him I'll bring some calipers and measure the thing. Then I can at least get some idea if it would even be worth trying to use it with the SKS. I'm guessing I would have to modify the adapter as well as the receiver to make such an unholy creation work.
You wanted a write up on how to do this. Here's the short version:
1. Remove material at front of magazine well to make room for XCR magazine.
2. Grind bolt so it no longer has rails that lock into the magazine, taper at rear, notch in front, as shown in one of my videos linked earlier in this thread. Essentially you're making the SKS-D bolt (not sure if it's exactly the same).
3. Screw a piece of metal to the side of the receiver to make a catch to hold the magazine in.
4. You have to cut the front of the trigger group off a little so it will fit.
5. Modify the bolt catch so it works with the new magazine.
My videos show pretty much everything you need to do. I didn't measure anything while I did this. I just got the magazine and started hacking and slashing until it fit!
I would recommend waiting until I can get a look at my friend's BT adapter. That would be the way to go if it works!