We no longer publicize this method. Instead, you can go to the OpenSprinkler app’s repository:
https://github.com/OpenSprinkler/OpenSprinkler-App
download the repository, unzip it, and go to the www folder, click index.html, and add a controller that way. Or you can go to:
http://ui.opensprinkler.com
and add a controller (note: http and not https because most browsers prohibit mixed content)