See if this helps you.
https://developer.mozilla.org/en/Command_Line_Options#-override_.2fpath.2fto.2foverride.ini

Those cmn lines don't work. The browser just opens. Maybe they were for previous versions.

about:config allows me to make changes but I find no location saved with those changes which I can apply in a deployment. I found an article that says it goes to a .js file but that file is not reflecting any of the changes.

I found the prefs file for the about:config. I thought it was under Firefox but it was in the user profile. Thanks!

Still a problem... How do I force the prefs.js? When opening Firefox a new prefs.js is created in %USERPROFILE%\Application Data\Mozilla\Firefox\Profiles\????????.default\prefs.js. How do I inject the prefs.js which I created???

Thanks!

Found this:For new users that do not have a profile you can place files in the default template location.

That folder doesn't exist anymore, so you will have to create it. All files in that folder are copied to a new profile.
◦C:\Program Files\Mozilla Firefox\defaults\profile\ 

I'm good now. Thanks