Ian,
Your wife is truly an acomplished wildlife artist
Here is a link to purchase Ron Smith's scroll drawing book. It isn't cheap but it is the bible for learning a wide variety of scroll design:
http://www.fega.com/prodserv/BooksSC.asp?recidparam=251
Everyone who owns this book recommends it. With this book and Lindsay tools I would have been years ahead of where I started.
You will be in a good position when you learn to engrave high quality scroll. Your wife can design the game scenes which you will reduce and transfer to the workpiece. As you cut the game scene your wife can coach you on shading and textures. You should make a good team.
Cheers,
Roger