Jack,
There are several videos, books, and a kit that specifically address the topic of training dogs to find antler sheds which are available through Gun Dog Supply and other outlets. I think they run about $20, one being produced by Tom Dokken the maker of Dokken training bird bumpers.
I don't train dogs for hunting sheds, but these resources should get ye on the right path. Good luck.
Cheers,
Irishwhistler