Can't connect with SFTP and custom port

I administer a website that recently switched its connection from FTP to SFTP, using port 21001.  I tried to edit the connection profile in Contribute CS4 to SFTP, but don't see where to add the custom port. (Advanced options are for Proxy servers).  I tried to append the port number to the host name (:21001), but Contribute still won't connect.  I am able to connect to the webserver with the new settings using an FTP program.  What do I need to do to specify the custom port for the SFTP connection in Contribute?

Thanks,

Robert