I apologize to anyone I might have sent on a wild goose chase. After posting this subject the solution presented itself to me. What I did is this: after creating the FlyNodeType object I set the ID property. I then add the type object to the NodeTypes collection property of the FlyTreeView itself. Then when I set up the node, instead of setting the NodeType property, I set the NodeTypeID property which is read-write.
The question that remains is this: Can I derive my template class from a template class that is already in use by the FlyTreeView control so that I can still have radio buttons, check boxes, etc. exhibit all of the same properties and behaviors (i.e. data binding, styles) as are exhibited by other nodes?