How can I run a user script before any inline scripts run on a webpage?

I want to make a greasemonkey type script for firefox that runs before the scripts on the page. Greasemonkey scripts run after scripts on the page, so that won't work. The reason I need this is because I want to edit one of the scripts on the page. Specifically, I want to delete a script that forces the page to load inside a frame since having the page inside a frame breaks F5 (Pressing F5 makes the page jump back to the front page instead of reloading the current page). Also, I don't want to load the page through a proxy with AJAX and s开发者_如何学Gowitching to chrome/opera is not an option either. I was thinking maybe the Jetpack add-on would work but it seems to only have the same event that greasemonkey uses, DOMContentLoaded. Any ideas?

[edit 2013] Use the page-mod module of the Add-on SDK with contentScriptWhen = start.

older: Right, only newer Firefox builds (currently 3.7 nighlies, may later be added to 3.6.x) have support for running custom scripts before content-specified scripts. I wrote a prototype Jetpack-SDK module to take advantage of the new notification.

Is it a <script src> or an inline script? In the former case it can be blocked with a content policy (something adblock-like).