As mentioned on the Github Repo Readme Page under Technical, you may also use this plugin with

Firefox

1. Install Firefox Extension: Chrome Store Foxified.
2. Go to Chrome Web Store: SteemPlus.
3. Click ‘Add to Firefox’ button.
4. Note: About this extension

No Google account is needed for this to work. If you do want to install the addon permanently, you will need an account on this website (addons.mozilla.org) - this will allow the addon to be "signed".

Opera

1. Install Opera Extension: Install Chrome Extensions.
2. Go to Chrome Web Store: SteemPlus.
3. Click ‘Add to Opera’ button.
4. Click ‘Install’ button in the Extensions Manager.