No, that's the one, rename it (get rid of the .txt extension which I had to add to allow the file to be attached) and place it in /usr/share/mbarcode/plugins/pythonqt/

Then it should just appear in the plugin settings window (if you want to disable all other plugins and only have that one running) or otherwise it will be listed in the results window when you scan an EAN/ISBN barcode.

You'll need to install pyside from extras-devel (if this script were packaged up correctly rather than just a single file, that would be a dep to be automatically installed.)

It's just Python code, take a look at it, should be pretty easy to understand what it's doing, etc.