Getting $comments outside the comment template

I have a ajax request hooked on “template_redirect” (the ajax requests the post’s url), and I want to display only the comment template:

function get_comm(){
  if(isset($_GET['get_my_comments'])):
    $offset = intval($_GET['get_my_comments']);
    echo $offset; // offset will be the same as "cpage"
    global $comments, $wp_query, $post, $id;
    print_r($comments); // nothing ?
    print_r($wp_query->comments); // nothing ??
    wp_list_comments('type=comment', $comments); // same :(
    exit();
  endif;
}
add_action('template_redirect', 'get_comm');

the javascript part works and it’s like this:

   $("a.show-more-comments").live("click", function(){
      var offset = $(this).attr('rel');
      var list = $(this).closest("#comments");

      $.ajax({
        url: "<?php echo get_permalink($post->ID); ?>",
        type: "GET",
        data: ({
          get_my_comments: offset
        }),
        success: function(data){
          list.append(data);
        }
      });
    });

The problem is that $comments or $wp_query->comments don’t seem to be initialized. What am I doing wrong here?

$comments, or $wp_query->comments, is initialized by comments_template(), which you call in your template file when you want to load the comment sub-template file. So at the time of template_redirect it is not yet initialized. As Chris said, you should call get_comments() and pass it the post_id of your current post.

If you’re doing AJAX calls, even not from the admin side, you can use wp-admin/admin-ajax.php and use special actions hooks. This shortcuts the usual post queries, which you don’t need anyway.