Connecting User Accounts to Third Party Social Sites

[Chris B]

I'm trying to enable my users to connect their accounts with third party social networks like LinkedIn and Github.  I don't want my users to be able to create accounts on my site with those links, just connect their existing accounts.  Django-SocialRegistration looks best, but I can't figure out how to get it to get it to not try and create a new user account.  Are there any other social libraries that would work better?