how to list comments outside wordpress using wp_list_comments

Hello,

I want to list the specific post’s comments in a file.

I used

if ( !defined('WP_LOAD_PATH') ) {

	/** classic root path if wp-content and plugins is below wp-config.php */
	$classic_root = dirname(dirname(dirname(dirname(__FILE__)))) . '/' ;

	if (file_exists( $classic_root . 'wp-load.php') )
		define( 'WP_LOAD_PATH', $classic_root);
	else
		if (file_exists( $path . 'wp-load.php') )
			define( 'WP_LOAD_PATH', $path);
		else
			exit("Could not find wp-load.php");
}
// let's load WordPress
require_once( WP_LOAD_PATH . 'wp-load.php');

?>

to load wordpress in a file named load-comments.php

Then i used wp_list_comments(); to list the comments.

But i know that the function is outside post loop so i am not able to list the comments. The thing i want is

$post_id = "5 or 6 or 7, i will change this using parameters" ;
wp_list_comments();

Hope you understand my problem