New Outlook Web App - adding other user's calendars

How do I add other users' calendars in the new version of the Outlook web app? On the old one it was just a case of right-click 'People's Calendars' and then open calendar, and select them from the address book.

The only thing I can find in the help files is an indication that if someone invites you to share their calendar and you accept, it will be added. This is of no use - we need any user to be able to add anyone's calendar themselves (all calendars have read-only access to all other users).

Thanks