Howdie,
I know of the more prominent schools in the East such as Heart Wood but I'm not familiar with them since I decided to got the route of an apprentice ship. I couldn't afford the courses which offered any real learning curve and provided a substantial skill set. I could afford, however, taking 4mo. out of my normal routine to do a paid apprentice ship. Its not like years gone by where working for timber framing priests in Japan the apprentice can practice the art of pushing a broom (for years).
That said, if you can't afford the time and damd the expense, I know of a shcool in your part of the world called North House Folk School, and they teach timber framing. I know nothing about it, only that I received a post from Clark Bremer who teaches there. Its located in Grand Marais, Minnesota.
You can check out thier course below or contact Clark as well. Maybe you can do an apprenticeship with him!!!! You can learn alot from just going to raising. Find a list of timber framers in your area using the Guild's membership website and search for members by area.
Time to get the kids off to school. Hope that helps.
Ian
http://www.northhousefolkschool.com/classes/Timberframe.htm clarkb@northernlightstimberframing.com