I am sorry for the potentially awkward question, but does anyone know how I can figure out how this 9-pin serial is wired, without tearing it apart?
Am I supposed to be able to see how it is wired by looking at it?
You can do a continuity test1 with your multimeter to find out.
Also, here is an image of the pinout for a male connector:
Assuming your connector counts from 1 to 9, you only have to test where pin 1 is and you know the rest.
1: with a continuity test you check whether there is an electrical connection between to points, i.e. if it conducts. You can check what wire is connected to what pin with such a test.
That is an IDT (insulation displacement technology) socket where the contacts actually press through the insulation to connect to the wires. What you want to know is that the wires are an interleave of the two rows shown in Keelan's pinout diagram.
From one end to the other, the wires correspond to the following pin numbers:
1, 6, 2, 7, 3, 8, 4, 9, 5.