Hi, Tom-
The Grand Lodge of Massachusetts offers a One-Day Class once every three years. Although nothing has been scheduled yet, the spring of 2009 would be the earliest that such a class might be conducted.
Although the One-Day Class is a good opportunity for some men to join the Fraternity, almost every Mason would tell you that the best way to join the Fraternity is through the traditional method, one degree at a time over the course of three months. In a One-Day Class the degrees are witnessed. In the traditional format candidates participate in the degrees, which makes for a greater experience. Even if you have a situation that might make it difficult to take your degrees in the traditional format, I encourage you to explore that option with the lodge you would like to petition for membership. They might be able to make arrangements that would accommodate you.
-Robert