Run code before web player starts loading

Is it possible to run even a single line of code before (or at the same moment) the web player starts loading? [The question here][1], is exactly the functionality I need. If it works with sound, how to achieve it within script? At the moment, I have to load at least 1 scene before I'm able to do anything.

We're using facebook unity SDK and I'd need to run some JS-injections during the first loading screen. [1]: http://answers.unity3d.com/questions/51741/how-to-wait-until-everything-is-loaded-before-star.html