Yeah, I had the same problem when connecting my hypercom (there are no markings to tell you!). Eventually I just took a chance and tried one way then the other. It seems that fitting in the wrong orientation does not cause any damage but you won't be able to open the high-speed serial port with your TCP/IP software. Of course, someone else may know the correct way to fit it...
As for the extra pins, you will have to cut the two next to the ones you attach the connector otherwise it won't fit. That's what I did and it works fine.
