Amongs Google PageSpeed ranking factors is one regarding a Content Delivery Network, that wants to use subdomains or a CDN for distributing content. If you have basic DNS and HTML knowledge you can do these easy steps:

  1. add to your DNS Aliases (A records) with the name and in order to point to the same place as
  2. edit your theme header.php file and change the adresses of the css and js files to do this with the plugins also.
  3. go to your media options in wordpress and put full URL path to files to, as seen below:

Cheap and fake cache for your blog

That is all. This can be easily done using CDN rewrites or WP-Supercache after completing step one.