- Unzip the package
- Place the folder somewhere on your computer where it will not be deleted
- Open Chrome and type "chrome://extensions" into the search bar
- Find and enable the switch for "Developer Mode"
- Click the button that says "Load Unpacked"
- Select the folder you copied in step 2 (there should be a file called "manifest.json" in this folder)
- Turn off "Developer Mode"
- Unzip the package
- Open Firefox and type "about:addons" into the search bar
- Click the gear icon and select "Install Add-on From File"
- Open the included file ending with ".xpi"