Hey, there's no problem! If you've already really read the FAQ, then you have to know the answer
Well, it doesn't matter that you have manual proxy settings in an other browser, to get it work you need changing the next lines:
pref("network.proxy.autoconfig_url", "192.168.0.1");
pref("network.proxy.type", 1);
These are my settings, just change them in your 'all.js' file to yours and let the other lines as you changed. It should work.