The external website would need to have the position marked up and you would need to discover the id for that position. Load the page and then use view source to look at markup then try to find a tag with an id close to the position on the page you want link to, for example a <div id="divlink"> then in the url of your link you add the #divlink e.g. href="http://www.somesite.com/sompage.htm#divlink"