Have you looked at this plugin? http://wordpress.org/extend/plugins/cdn-rewrites/

From the description of the plugin:

Basically, this plugin allows a WordPress user to specify two important variables: an orgin host (your site) and a "destination host" (cdn host). It will then find all the static contents from that origin host and rewrite them into the destination so that they will be delivered from there.

This seems to be what you need?

Have you looked at this plugin? http://wordpress.org/extend/plugins/cdn-rewrites/

From the description of the plugin:

Basically, this plugin allows a WordPress user to specify two important variables: an orgin host (your site) and a "destination host" (cdn host). It will then find all the static contents from that origin host and rewrite them into the destination so that they will be delivered from there.

This seems to be what you need?

------------------------------ EDIT

If trying to avoid using plugins, here is a great article about it: http://www.cyberciti.biz/tips/wordpress-cdn-content-delivery-network-configuration.html

However, I have never tried this method. But it looks like a clean solution.

Have you looked at this plugin? http://wordpress.org/extend/plugins/cdn-rewrites/

Have you looked at this plugin? http://wordpress.org/extend/plugins/cdn-rewrites/

From the description of the plugin:

Basically, this plugin allows a WordPress user to specify two important variables: an orgin host (your site) and a "destination host" (cdn host). It will then find all the static contents from that origin host and rewrite them into the destination so that they will be delivered from there.

This seems to be what you need?