I’m guess you could run wordpress from a subdomain as long as you have a way of pointing all the domains to that subdomain. The easier way to do it would be on install wordpress on one domain name and run all the others on ubdomains/subdirectories of that domain name. Use Donncha’s Domain Mapping plugin to point the domain name you want the subdomain/subdirectory.

As for running other blogs in subdirectories, like I mentioned I haven’t tested it with subdirectory installs so I really don’t know whether it would work. Also I don’t think this version will work with the latest version of wordpress just yet. I’m working on an update that I should release later this month.

The easiest way to do this would be to install wordpress in root say using domain1. To have a VHOST install you need wildcard dns enabled for domain1. There are loads of instructions on the web on how to do this. Just ask your hosting provider they should be able to do it.

Once that is done and wordpress is installed in VHOST mode, set up another blog on wordpress in a subdomain of domain1. Then park domain2 on top of domain1 and use Donncha’s Domain Mapping plugin to map that domain name to the blog you want. That should do it!

If you want you could set up a subdirectory install of wordpress, set up a blog in a subdirectory using wordpress and use the plugin to point domain2 to the blog.

Sorry for the late reply. I also apologize about the documentation. Writing plugins is something that I do in my free time and I haven’t had very much of that lately hence the lack of documentation.

Firstly, please note that the current version of the plugin (0.1.1) does not work on WP3.0. There should be another release later this month/early next month with support for WP3.0. As mentioned in the readme, I haven’t tested this plugin on subdirectory installs or with WP installed in any directory other than the root directory. In theory, it should work but again I have to stress that I have not tested it in these scenarios so I am not sure what will happen.

Regarding the setting up VHOSTS, it is not something you can do from within cPanel or Plesk. Your hosting provider will have to manually set up wildcard subdomains for your account and very few hosting providers allow you to do this.

However I am not sure that this plugin is what you are looking for. What this plugin does is allow you to run a blogs on subdomains of say domain1.com, domain2.com and domain3.com with WP installed on just one of the domain names (eg. domain1.com). WP would have to be installed on the root of domain1.com. domain2.com and domain3.com will have to be parked on top of domain1.com (if you are not sure what this means Google “domain parking”)

In your case what I think you are trying to do is run WP blogs on domain1.com/blog and domain2.com/blog without installing WP in the root directory (ie. public_html). The easiest method would be to run to separate installations of wordpress in the subdirectories. That would definitely work. Your method could work as well although you would need to use Donncha’s domain mapping plugin to map the domains to the blogs. Either way, my plugin is definitely not what you want.