Starting User script in Greasemonkey

Question

Is it possible to run a user script before the page and DOM loads?

Answer 1

Only if the user script runs on google chrome atm. Greasemonkey may support this too someday:

// ==UserScript==
// @name My script
// @description It's really neat
// @run-at document-start
// ==/UserScript==

Answer 2

As Erik Vold said, Greasemonkey cannot do this unless the browser is Chrome.

But, if this functionality is needed on any other browser, you can write an extension.