Login with Community Builder email

That's not something that could be easily supported in JFBConnect. Community Builder has it's own, very separate, login method that isn't easy for other extensions to tie into. We support what Joomla supports for authentication, which is the username for the user.

What I'd recommend is setting the "Registration Display Mode" option to "Register Only" to hide the Login portion of the page. Then, you can use the other methods to let a user know they can connect their accounts, like:
* Enable the "Automatically Link Users by Email" setting
* Using the SCLogin module to let already logged in users link their accounts
* Add "Connect" buttons to other parts of your site to let logged in users know they connect their existing account to a social network

I hope that helps give you some ideas, even if it's not specifically what you were looking for.

Thanks,
Alex