Is there any way to prevent FirefoxPoratable from reading the registry? I have tried the ini file and all its settings with no luck. I have also tried profiles without success. I need to run Firefox with an old version of Java for internal use and leave the local copy set to the latest version. No matter how I configure either the settings from one change the other. And the registry is always read and the plugins registered there are used by both and across all profiles.
If you use a legacy version of jPortable in the right place, it should, in theory, use that. I believe current versions of Firefox will prohibit using an older JVM no matter what for security reasons, though.
You can disable some plugin scanning here:
http://kb.mozillazine.org/Plugin_scanning
Sometimes, the impossible can become possible, if you're awesome!