With SuperEdi you can edit files directly on a FTP server. Just enter the URL to the file in the address bar and press enter to download the file. When you save your modifications, the file will be uploaded to the same position on the server.
The URL to an FTP file has the format ftp://server_name/path_name/file_name. If your server requires authentication by login and password, you can include both in the URL like this: ftp://login:password@server_name/path_name/file_name.