Extension for MathML fonts

Hi all,

I'm trying to write an extension that installs fonts necessary for the 
Mozilla's MathML engine [1]. The idea is to store downloadable WOFF 
fonts in the extension content and to make them accessible (via 
@font-face directives) to the user agent stylesheet for MathML [2]. I'm 
wondering if there is a way to override this stylesheet ("override" in 
the chrome manifest does not seem to work for this resource) or 
otherwise what is the appropriate way to achieve that result? Ideally, 
this extension should be compatible with all user agents based on Gecko, 
but restricting it to Firefox is also fine.

Thanks.

[1] https://developer.mozilla.org/en/Mozilla_MathML_Project/Fonts
[2] 
http://mxr.mozilla.org/mozilla-central/source/layout/mathml/mathml.css?raw=1 
or resource://gre-resources/mathml.css

-- 
Frédéric Wang
maths-informatique-jeux.com/blog/frederic