On a system set with "Automatic Proxy", you need to download the proxy file and locate the server name. The file will contain a function that is used for routing proxy requests. Somewhere (likely near the top), it will contain the name of the server that is acting on the file. Once you have that server name, you can set up the proxy in Talend.
It does not work for me (and others) in TOS 6.5.1... It works well in TOS 6.5.1M4 !