Url rewrites for unique site names in Wordpress Multi-site without subdomains or subdirectories?

Is there a way in multi-site WP3.0 to pro开发者_如何转开发vide unique site names without using subdomains or subdirectories? For example, my multi-site name is sites-d.ourdomain, but I want the urls for each site instance to look like this:

[site1].ourdomain (instead of sites-d.ourdomain/[site1] or [site1].sites-d.ourdomain)

Our clients expect to have the name of their organization followed by ".ourdomain" on every page of their site. Is there anyway I can pull this off? If so, how? I suspect this might be possible with rewrite rules, but my system administrator suspects this may be buggy.

Drupal, by the way, pulls this off by using duplicate CNAME records in DNS.

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Im not sure if this will help, BUT, ive just finished a little wp3mu site using the domain mapping plugin, our site structure was.

site1.oursite.com
site2.oursite.com

then using the domain mapping plugin, and our hosting plesk panel we were able to create an alias for our main site, using there domain name, this domain name then mapped to our servers ip and the mu site, which in turn produces there own domain name as the url to the wp site,

ie:
site1.oursite.com, + alias + domain mapping = http://www.theresite.com
site2.oursite.com, + alias + domain mapping = http://www.anothersite.com

so instead of creating a whole bunch of wp sites, we used the wpmu, configured it so each blog was its own top level domain, much like its own wp site.. if that makes sence,

like i said not sure if that helps, but it def works...