That's not something JFBConnect can do on it's own, it's something you'd have to code on your own. Additionally, you'll need to make sure that your custom registration page is calling the JFBConnect registration function so that the new Joomla user is properly associated with their Facebook account.
So, you'd need to redirect the user to a page that is going to popup our registration form (or at least the fields that go along with it and submit to the right place). Once you do that, our registration form can automatically display the user's profile information for verification. Otherwise, after they've authenticated, you can easily fetch whatever information you want to prefill fields.
Hope that helps explain a little. If you have ideas on how you're going to implement the above, we can gladly try to help.
Thanks,
Alex