Due to space considerations, some of my illustrations were not able to be included in the Journal of Light Construction article. These show, among other things, how the pieces are laid out on the stock that they're cut from. I didn't have to worry about a finished interior, but one option would be to frame a rectangular opening rather than the angled opening shown in the JLC photos, and then the ribs would look something like the final drawing here.
Also, although it doesn't show in the article, the garage is not a rectangle. Due to site constraints, a rectangular two car garage would not fit. Instead it is a polygonal shape with only one right angle. In fact, from one view you can see both sides of the garage at once. The flat roof on the back of the garage hides this, though.
Here's a link to the JLC article.
http://www.jlconline.com/framing/building-an-eyebrow-dormer_o.aspx?dfpzone=general

Or, if this all seems too complicated, there is another way.
http://www.digiconsoo.com/