It’s not exactly impossible, but it is very difficult. All new E-mails, sub-domains, and whatnot must go through the panel. There’s no way around that, what you can do is set up a a system to take the info from your site visitor and pipe it into the panel.
I’ve posted about this a few times before, and you should be able to search and find that info. Check the wiki too, for instance the dynamic DNS article has a script that logs into the panel to make IP changes - that should serve as a good example of what would need to happen.
art.googlies.net - personal website