Rewriting URL's conditionally for CDN Origin Pull

[olicity]

Our website http://olicity.com is currently not using a CDN, even though I had it running earlier today.

I need to find a way, without a plugin, preferably the Genesis way, to hook/filter into rewriting every URL in the html output if certain criteria is met.

So for example:

if file is in wp-content/uploads change http://olicity.com to http://cdn.olicity.com

We are set up with an origin pull CDN with Amazon Cloudfront and DNS has been created. I also verified that everything works correctly with W3 Cache, but that plugin is simply to heavy as we are running Google's mod_pagespeed on the server with better success for cache, minify and other optimization techniques.

Please help.

Thanks,

Kim