WPMu domain; http://cynix.us
Blog within WPMu setup: http://test.cynix.us
Requested domain example: http://drmike.uni.cc
What's really funny is I've been thinking about this backwards. Take the requested domain and forward it to the WPMu URL. It works the other way.
- Point the requested domain to the nameservers of the WPMu domain. (Ex: tell the registar for drmike.uni.cc to look at ns1 and ns2.tdjc.be. Those are cynix.us's servers.)
- Park (not addon, not host. Park) the requested domain within the account of the WPMu account. For example, I go into the CPanel backend for cynix.us. CPanel -> Manage Parked Domains -> New Domain Name -> Add in the requested domain.
- WPMu time. Open up Dashboard -> Site Admin -> Search for the blog within the WPMu setup and edit it. Look through that page. On my very basic setup at cynix.us, I see the URL of the blog listed 4 times. Edit those four occurances from the old URL to the new one. If it has the 'http:// in there, keep it in there. Click on Save changes.
The setup should now work.
One last bit. If you want to old URL to point to the new one as well, you have to setup a redirect within the .htaccess file within teh root of your WPMu install. For example:
RewriteCond %{HTTP_HOST} ^test.cynix.us$ [OR]
RewriteCond %{HTTP_HOST} ^www.test.cynix.us$
RewriteRule ^(.*)$ http://drmike.uni.cc/$1 [R=301,L]
Hope this helps,
-drmike