Rapunzl wrote:

Tie him to a chair and his hands to a keyboard?
Sorry, couldn't resist. Anyway, the only way you can do this is to create a plugin that triggers OnLogin or something (not a coder, can ya tell), but I'm not sure why you wouldn't just include it as required on registration. I'm thinking it could irritate users.

Need more than just a plugin - most likely you would need to hack CB to not allow cancel during profile edit.