I had issues getting the module to work correcly with the theme I am using ( nitobe ), in particular the preview button was never removed from the comment form because the nitobe theme applies an id of edit-submit-$number to that button. A quick hack is to comment out lines 27-31 in live.comment.js and add this code:

      $('form#comment-form input.form-submit').each(
        function(i) {
          if (/^edit-submit/.test(this.id)) {
            $(this).siblings("input#edit-preview").hide();
          }
        }
      );

This is not really a general solution, it might be better to have some additional settings for the module to specify selectors.