Actually I did find an answer by one of the devs, that says:
There's a button under the "Station Players" link on the left side of the Vanguard LaunchPad that says "Test Server".
If you don't see it, then you may need to perform a "repair" using the North American version digital download installer that is found on our web site at:
http://vanguard.station.sony.com/en/install/