I finally have managed to get the wp-hive plugin working, but not without "a few" problems here and there.
The main thing I struggled with was the 5th point in the Documentation: "Use your Webserver Administration (Cpanel, IIS, etc..) to point any domains you want to use in the hive to the Wordpress directory."
I find "point it to the WordPress directory" a bit vague. My host (Namecheap.com) finally helped me and told me to point it to: public_html
I think it is important to know as that simplifies things a lot, but of course I don't know if this is also the case in other hosting environments...
Also the table-prefix can use some clarification: Basically you can keep it as is (wp_) in your config-file as the plugin changes it anyway to that.
When your subdomain consists only of 2 letters, you can only get the plugin to work if you manually change the prefix for the subdomain in the wphive_hosts table!
This is important, because if you don't do anything the plugin automatically adds a dot (ab._) and since that is
an invalid character for the prefix, you can try forever, but you won't be able to make it installing WordPress on your subdomain.
