The sponsor can absolutely select the role when creating an account manually logging into the Amigopod with an operator account.
I think in Scott's case he is trying to get the same role selection but through the guest driven self registration workflow where an email sponsor approval request is sent.
In this case the sponsor is displayed with a single page approval portal where the request can be confirmed or rejected.
I am not aware of a way to customize this page to include role selection.
Cam