I run an enterprise of 24K employees that all have local administrative rights; users have installed firefox over the years into multiple different locations, and all users have computers with multiple disks/volumes, so knowing up-front where to put a configuration file to customize Firefox has always been a challenge/impossibility. The GPO additions in Firefox 60 allow me to configure 99% of what I need to, however there are certain other settings that are needed (one example is general.useragent.override.<domain> which is necessary to tell our SSO system which IWA system in the corporate forest to bounce the user to for IWA to work properly). I can get things working perfectly if I confgure the settings manually in about:config, but how can I either 1) define the settings in a GPO item or 2) define the URL of a json/js file that contains the settings via GPO. As stated, I know I can use a local file to set this up, but the whole point of GPO is to configure software centrally without regard to where in the system a user may have installed it.