If you find the position uncomfortable, approach it by degrees. Never force. But gently ease your hand as far into the position as you can COMFORTABLY, and then while there, experiment a little with that rotation movement, see if by doing the rotation in tiny increments you can perhaps increase the ease with which you can sink into that position. It is NOT stretching. Feldenkrais taught us about the stretch reflex: if you stretch a muscle its automatic response is to shorten itself. No, here we are teaching the muscle neurologically, through sensation, how to lengthen more efficiently.
I only like to say that I have watched and read your demo with much interest, and what you write here sounds very convincing to me too. Even although English is not my native language i consider buying your DVD.
Only a little thing: although I normally play with curved fingers, my both pinkies tend to remain straight while playing. Someone told me I should do something against this probably bad habbit. Not easy after almost 4 decades of playing. I have seen in your demo that your pinkies weren't curved either. Does it make sense to overcome that habbit in my case?