Can anyone explain to me how to specify global preferences for Firefox 3 in openSUSE 11.1?

For Firefox 2 I was putting stuff in to /usr/lib/firefox/mozilla.cfg. Stuff like

pref("browser.startup.homepage", "");

and in /usr/lib/firefox/greprefs/all.js I put a line to reference the mozilla.cfg and set general.config.obscure_value to 0 because I just can't be bothered with the byte shift 13 stuff.

But with openSUSE 11.1 there is no /usr/lib/firefox/greprefs directory. The greprefs directory is there in the download of Firefox 3 from but in Firefox 3 as provided in openSUSE 11.1 it's not there.

I've found /usr/lib/firefox/defaults/preferences/ and by looking at the output of strace worked out that the contents of that directory is read in reverse alphabetical order. If I create a file in there called a.js and specify a few settings in there then some take effect, e.g. disk cache, and some are ignored, e.g. homepage.

So where am I supposed to put settings such that they take effect for all users and lock the settings that I want to prevent users changing?