To tell the truth, I really wanted to cheat when making this part this past weekend. Greg's extruder is now so well tuned, that it will probably be one of the first upgrades I'll print myself when my repstrap goes on line.
But, it is all about the journey. And I had lots of fun hacking this extruder together
I do not expect anyone making this thing, but here are instructions for the foolish, or the brave (or possibly both)