To achieve cross-blogging the target blog must be Metablog API enabled. Its then a simple case of setting up the target URL in my case it would be: http://www.geekswithblogs.net/ajames/services/metablogapi.aspx and then adding username and password. This is all done in the Ping & Cross-posting section of My Blog in Community Server.
Previously posted at blog.Solidsoft.com