The question is not clear. You mean you want multiple domains to show the same X3 website? Yes that is of course possible as long as you set it up like that from your host, where all domains point to the same X3 root folder.
But then why not instead REDIRECT all domains to your choice of primary domain? That is much better for SEO and less confusing to visitors. See my post here:
viewtopic.php?f=62&t=9080