WP8 GDR2 supports CardDAV and CalDAV when adding a Google account. It was very easy--pick Google when adding an account and the rest was magic; contacts and calendar now sync.
I have a Yahoo! account (whose servers support CardDAV and CalDAV ) that I'd very much like to sync the calendar and contacts as well. When I add the account in my phone as a Yahoo account type, however, it just syncs mail with IMAP and ignores the rest. I attempted also to add the Yahoo account as a Google account, thinking I'd be able to override the server addresses (I was wrong).
Is there any way to add a Yahoo account to a GDR2 WP8 device with mail, contacts and calendar?