CreateUserWizard - manipulating the Create User event

I am trying to customize the CreateUserWizard such that the username is an email address. How do I add a RegEx validator for email to the username? Also, i want to set the email field in the CreateUserWizard to the email address that is in the Username textbox...how would I accomplish that?

Ive done alot of searching on customizing the CreateUserWizard, but they all refer to adding a new step and then adding new information which may go into other tables or something of the sort.

Thanks
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