wouldn't it make more sense to switch out the default comment form for the facebook comment form?
also, i found this bit of documentation within the theme to be misleading:
Note: Your themes must use the action "do_action("comment_form_after");" or the function "commnent_form();" to work. (look in your theme, in comments.php file)
your theme doesn't require comment_form_after OR comment_form functions.... as far as i can tell you MUST have the do_action('comment_form_after') hook... which i suspect is less prevalent than comment_form()
otherwise i am really digging the plugin. nice to have all the FB stuff in one place.