Alex,
Secure Certificates are limited by domain name, not by account name. My understanding is that if you put the domains into one account you'll still need to do similarly to what I wrote.
If you're sharing among one user, yes, you can do it in the user account, and get the accouting for the user's use of resources, but you'll still need the subdomain and the Certificate issued for the subdomain. You can't have one Certificate answer for multiple domain names, even if on the same IP#s, without incurring an error every time a visitor visits the site.
So I really don't understand what you mean by traditional way. Could you please explain in more detail?
Thanks.
Jeff