Vincent,
That's not a setting from JFBConnect itself, it's configured within the Comment widget itself or at Facebook. If you're logged into Facebook with an account that's an administrator of the application, in the top right of any comment box, you should see a "Settings" link. Click that, and enable the "Other login providers" setting.
If you can't see that settings link, you can go to the link below, select your application, click Settings, and enable the same setting.
developers.facebook.com/tools/comments
Hope that helps, and very glad to hear you enjoyed the JDayNYC presentation. We loved getting out there and had a great time!
Thanks,
Alex