Rewrite URL that use a Custom CDN

[Franklyn]

I'm currently use a Custom CDN and I want to know if exist a way to rewrite all urls that the CDN use so that I can give some GET Variables.

URL now : http://cdn.mywebsite.com/js/xenforo/xenforo.js
URL after: http://cdn.mywebsite.com/js/xenforo/xenforo.js?mytoken=hash

The token Hash will be generated through php.