As before, I'll post this as a project update on the flapbook site, but before I bother with writing about it, I wanted it on a server instead of just local. I turned down the JPEG quality, but it's still 300K (it's being scaled to fit in this blog. Scalable outside it.)
The update here is that I have the code fairly correct for turning the pages with the Kindle-esque page controls. It gets a bit wonky if you only go halfway then come back. The flaps all now flap, too, but once you get through the book, only the flaps on pages on the left will work. As proof-of-concept, though, and with the assets I had, I believe I'm very close.