The shape of the stomacher is basicly the bodice front, cut straight across the bustline. I didn't bone it at all, I put a layer of buckrum between the fashion fabric and the lining. And no, the Hunnisett pattern wasn't for a zone front dress, but it was really easy to alter... I made a mock-up of the bodice as it appears in the book, and just played around with folding the front up at different angles until I thought it looked right. I used the same bodice pattern to make the stomacher, and just changed the shape and length of the front point, and cut it across at the top.

Hope that makes sense! :-)