1.
COPY all of site_template into the new location, next to the others.

2.
Ensure it contains a .htaccess file that should have been copied over with it.

3. 
Copy a current config.php file into that dir, and optionally a custom.css

4.
Open up permissions so that the webserver can write to that directory.
This is insecure... but that's how this system works.

5. 
Set up host and DNS pointers to serve that site directory

6.
Visit it, but it will not work just yet. instead visit http://site.name/setup.php
That will do magic on the server to make the theme and include files available.