How to require login or register in comments-popup.php

Can anyone tell me how to require registration and login to comment using the comments-popup.php page? This seems to be built into the comments.php page but I would rather use the popup version to keep the page cleaner.

When I tried to incorporate bits of code from comments.php into comments-popup.php, I kept getting odd errors about unexpected curly brackets or else elseif bits

I am pretty good at reading the structure of the code but I’m not a php developer… I’m good at commenting out bits to test where the issues are but just couldn’t get this to work.

So, ? Is there something I could read about this?

Here’s my code from the comments-popup.php page:

[moderated – long code deleted]