The nikkyo I hope to learn before I die is a little different. The emphasis is not on pain compliance, but on kuzushi.
It's out there if you really want it. You just need to find someone who can do it and can teach you how to do it. This, unfortunately, may be a harder task than actually learning how to do it. That said, learning how to do this requires a complete reprogramming of everything you do. You can't just learn 1 'trick' and leave everything else the same. It doesn't work that way.
I knew I had met my (then new) teacher when he could not only "do" it to me however and whenever he wanted, but could also clearly explain it and and teach ME to do it.
I taught the idea behind it (on a *very* basic level) to a visiting lady in about 1 or 2 hours using 2 movements from one of our 'kata.' We played with them all night, and she picked it up quite quickly.
At the end, I did "nikyo" with her. She looked puzzled and said it didn't feel like I had done it correctly because it didn't hurt. I asked her to move her feet and she found she couldn't. I asked her to let go and she found she couldn't. Then I asked her, "If I own your entire system, why do I need to hurt you?" She broke down in tears.
The lady in question had *very* flexible wrists and was used to the men in her dojo cranking on her joints in order to make the technique work. Apparently, realizing that all the pain and injury was unnecessary caused a strong emotional release. I let her cry and said, "I understand." Then we, as Jun might say, got back to training.
I don't know if she ever trained again once she returned home, but she did write our dojo a nice thank you note for the training time. She is a credit to her teacher.