Is it possible to allow guests to create comment entries but enforce a login or registration before it can be Posted?

My client wants visitors to the site to be able to use the comments editor on posts without first requiring a login or registration - but to enforce the login before they are actually allowed to Submit the comments.

I can see that it is possible to allow guest comments, and that it is possible to enforce a login before allowing any access to the comments mechanism - I just haven't found a way to only enforce a login when the Submit button is clicked.

Is it possible please?

A second question : I am using SLogin which enables logins through Facebook, Twitter, etc - Is there a way to integrate this into EasyBlog so that the SLogin mechanism comes up when clicking the Easyblog login button?

Thanks for any guidance.