Keyfixer is a patch utility that modifies the Firefox configuration file named platformHTMLbindings.xml (kept inside the zip file named /Applications/Firefox.app/Contents/MacOS/chrome/toolkit.jar) with the appropriate key board shortcuts. For example, these are the lines that change Home/End to go to the beginning/end of the current line instead of top/bottom of current edit window.
<!-- Additions to fix home/end -->
<handler event="keypress" keycode="VK_HOME" command="cmd_beginLine"/>
<handler event="keypress" keycode="VK_END" command="cmd_endLine"/>
<handler event="keypress" keycode="VK_HOME" modifiers="shift" command="cmd_selectBeginLine"/>
<handler event="keypress" keycode="VK_END" modifiers="shift" command="cmd_selectEndLine"/>
The question I have is whether similar changes are possible within the keyconfig firefox plugin. If this is possible, it would be much easier to maintain because you have to uninstall Firefox keyfixer before upgrading firefox.
I see a lot of potential in keyconfig because it's a firefox plugin, and is something that should be in Firefox anyways, but right now I can't make it work better than the keyfixer patch.