Because our website has too many pictures, I want to move them to another domain: http://www.xxx.com/images

I set up the code under:includes\configure.php：
Code:
 define('DIR_WS_IMAGES', 'http://www.xxx.com/images/');
I need to change the <img src=bmz_cache/f/f80d0fad6742d2bc1025f58181039149.image.120x120.jpg">to<img src=http://images.xxx.com/bmz_cache/f/f80d0fad6742d2bc1025f58181039149.image.120x120.jpg">

how to edit IH4 code？


I have tried to edit IH4 includes\extra_configures\bmz_io_conf.php
Code:
$bmzConf['cachedir']    = DIR_FS_CATALOG . 'http://images.xxx.com/bmz_cache';
and IH4 admin\includes\init_includes\init_image_handler.php 44-47 line

Code:
   DIR_FS_CATALOG.'http://www.xxx.com/bmz_cache/.htaccess',
            DIR_FS_CATALOG.'http://www.xxx.com/images/watermark.png',
            DIR_FS_CATALOG.'http://www.xxx.com/images/large/watermark_LRG.png',
            DIR_FS_CATALOG.'http://www.xxx.com/images/medium/watermark_MED.png',
but it didn't work.
my serverinfo
Server OS: Linux 3.2.0-2-686-pae
MySQL 5.1.66-0+squeeze1-log
HTTP Server: Apache/2.2.22 (Debian)
PHP Version: 5.4.0-3 (Zend: 2.4.0)