Wildcard (subdomain) with RackSpace

Hello everyone,

I have run into what I think is a big problem -- I bought a Cloud Sites hosting solution with RackSpace. Their service is excellent and the technology is great, but... As I'm installing WordPress and the great plugins from WPMU, I wanted the member to my new service to sign up with a sub-domain like http://yoursite.mysite.com. Now it turns out that they do NOT support this. I understand that this is referred to as "wildcard domains" (?). And I don't want my new subscribers to have a sub-DIR
like http://mysite.com/yoursite...

What do I do? I hate that I have to cancel with RackSpace and find a new solution, but is that what I have to do, you think?

Please help - I would really appreciate anything you can do for me. It is really a total bummer.

Cheers,
Soreng