I want to run Firefox Portable from a locked, write only partition on a usb stick. However, that cannot be done unless I allow temporary writing to the host computer. I do not want to allow that. Is there any way to change configuration files or other source files that will allow this kind of use?
Not unless you alter Firefox itself and recompile it. If you do, it then can't be redistributed with the name Firefox anymore, though.
Sometimes, the impossible can become possible, if you're awesome!
Any idea of what would need to be altered?