I don't think there is any way to do this in an easy way.
I would personally create the new SC and make the root collection sort of a index page with clear links to the key sub-sites.
Then, backup/restore the site from the original SC and to the new SC and update the index information.
--Paul Galvin, Computer Generated Solutions (CGS)
Microsoft MVP - SharePoint
Blogging @
http://www.mstechblogs.com/paul
Twitter @
http://www.twitter.com/pagalvin