Framing Cornice Return

rbrothers2

I'm working on a new house that is to have boxed "Greek" cornice returns at each corner of the 6/12 gable roof. There is an overhang of 18" at eaves and rake.

The return box measures 36"x24" so that 18" is towards the facia and 18" is against the side wall. It will be wrapped by a 1x6 facia and either shingled like the roof (3-tab) or covered with copper (TBD).

The cornice return's roof is spec'd as hip (no porkchops). I have framed standard hip roof where pitches are equal, but I'm not sure how to start laying out and cutting these hip rafters (2 rafters from the end truss above the center of box to each corner... ).

I've ordered Will Holliday's book, but haven't received it yet, and don't know if he covers this topic.

Does anyone have any tips that might help me get started?

Thanks
Bob in Lone Oak, TX