Silent install Addons in Firefox 42.0

Hi there. I’m looking for a possibility to install Addons for Firefox unattended/silent. We use opsi for clientmanagement and automated installations. Now we have a couple of Addons that should be installed automatically on several Clients. Now I have downloaded all the needed .xpi files but I wasn’t able to figure out how I could install them silent. I already tried to copy the content of the xpi files to \mozilla\firefox\browser\extensions but it didn’t work. Moreover I tried to install the Addons via cmd-command/parameter which I’ve found in another Forum but it seems that this only worked for older FF Versions. How can I manage to install the Addons silent?

Please check out the documentation and mailing list in the Enterprise group. That’s where you will find help for this sort of thing.