This looks identical to the one that originally came on my Solidoodle2. You might check their replacement parts to see if their hotend would work.
http://store.solidoodle.com/index.php?route=product/product&path=63_66&product_id=59
Like a screw drive? I was wondering if anyone had tried that…
That’s just what I had in mind (although I hadn’t thought about the second nut for counter torque, very clever!)