David,

you are correct that the adjustment in cut angle is the result of backing the legs. The important thing with such a slight angle is to make sure you slope it the right way. It's easy to lay it out upside down.
The class I have here is great and the student's are really motivated, but I've been pretty swamped for my first three weeks here and haven't had much opportunity to lift my head and look around town yet. Hopefully this weekend will give me some time to do that. The weather is milder than Ianticipated for this region in January.
I won't be covering the Koh-ko-gen method in this three month course, but it might happen in the future.
By the way, you may be interested in a pair of courses slated for the Heartwood School in May and June in which this method will be explored in detail. We're planning to make a simplified splay-posted bell tower.