[Greasemonkey] Can greasemonkey set user prefs?

[Anthony Lieuallen]

On 8/23/2006 11:29 PM, beejamin wrote:
> Is it possible for a greasemonkey script to alter any of the Firefox
> settings (normally set in prefs.js or User.js on the fly? 

No, but a signed script could.  After getting elevated privileges, which 
involves a big security prompt dialog.

http://www.mozilla.org/projects/security/components/signed-scripts.html
http://www.arantius.com/misc/signed-scripts/