How to get rid of user_pwauth app

I once started with owncloud using the user_pwauth app for user management. I upgraded to NC and now, since my cloud is ever growing, I want to get rid of user_pwauth and migrate my users to normal db-based users.
I found the files:transfer-ownership occ command, but how can I transfer calendars and address books?
Can I accomplish this with some smart SQL statements in mysql?