Configuring preferences and options in Outlook.com
It is a very late answer but if your Outlook.com account has been migrated to the Exchange infrastructure, you can now.
- Go to System Preferences->Internet Accounts
- Click the + sign at the bottom of the left hand side of the window and click on Exchange.
- Type your email address and password and click on "Sign In". It will give you a message saying "Unable to verify account name or password". Ignore it and click "Next".
- On both the Internal URL and External URL fields, type "http://outlook.com" without the quotes and click on "Sign In".
- Confirm which features you want to sync (Mail, Contacts, Calendar, reminders, Notes) and click on "Done".
As of today, 11/15/2016, it seems you can only add only one Outlook account as an Exchange account on OS X 10.12.1.