Danny: You might want to try using the Finder's Connect to Server dialog box. In the Go menu select "Connect to Server...". In that dialog, you can type in a server address directly. For instance, if the IP address of your NAS is 192.168.1.2, then you could try mounting using the following string:

smb://username@192.168.1.2/

Replace "username" with the username you are using for the FTP session. It should then prompt you for a share to mount (or you could add the share name after the rest of that URL), and a username/password to use to login. If you want to save a form of bookmark to the server, in the Connect to Server dialog, you can click the + button to save the current server address string in the list view below.

Hope this helps...