I don't know the answer to your question. So, what I do when I short side myself is to just open the face a little and lower the hands to get a really high "flop shot" type trajectory. I also wouldn't mind knowing how to spin it a bit more as an alternative to this, but for now this is all I have. :)
I was hesitant to post a response, but will jump in -- I'd guess it's a combo of dynamic loft (the more actual loft given the setup and swing, the more backspin, and the more speed, the more spin - caveat on spin). If you open and lower the hands with the handle back, you are gaining loads of dynamic loft (backspin, trajectory) and creating a glancing blow. I doubt if this glancing blow helps spin -- but you gain gobs of trajectory, and the glancing blow allows you to come in with some speed, and get a ball that pops up, goes almost nowhere, and does nothing once it hits the ground.
The key is to experiment - now much to lower the hands, open? square? grip down how much? the shaft is backwards- how much?
Depends on the shot, the distance, slope of the green towards the hole.
Loads of practice.
I spend about 10-15 minutes each time at the range on this little shot... it sure takes the hit out of me, which is what I need to practice.