Our website provided a free download of AUSEnabler 1.0 for Mac. This free software for Mac OS X is an intellectual property of FurCode Project.
From the developer:
AUSEnabler is a free-to-use application for Mac OS for those who want a UI to switch to AUS in order to get further Sierra updates. After selecting a catalog, just open the App Store and update away. The app requires a working internet connection to fetch the latest catalog URLs.