The interface can be accessed at admin site-level (to configure site-wide repositories) as well as course level (to configure course-wide repositories) and user level (to configure personal repositories).
It should show a list of all repository instances that the current user is allowed to modify, and allow settings for each to be changed (or a new one added).
The admin site-level will be in admin/repository.php
The course and user level will be in repository/manage.php
The settings for all should probably go in `config_plugins` (Think about how to save contextid here, may be php serialized data).
Personal ones can go in `user_preferences` (and get saved in backups etc).