I finally got around to wiring mine up yesterday. So here are some fresh observations. . .
The ribbon cable has a standard header at each end. So, there are several ways you can skin this cat. You could cut up the ribbon, I suppose. My approach was to leave the ribbon cable intact, leave the header attached to the PCB, and solder a couple of leads to the PCB itself. It had a couple of solder pads that are grounded, so attaching the ground lead to one of those was easy. I soldered the signal lead to one of the legs of the switch. This was tricky, because it's a very small spot. I really wished for a third hand and more light. Anyhow I got it done, even if looks a bit ugly.
I used a length of old phone cable (two wires) and threaded it through a hole in the PCB, so if it accidentally gets yanked then the insulated part of the cable will take the stress, it won't pull the leads loose from the PCB. I still need to make a little cardboard box or something to surround the PCB and keep it from shorting against anything inside the PC case.
The original switch PCB and ribbon in the PC are left alone. I just unplugged the old ribbon and plugged in the new one. If the PC is ever used for anything else, it'll be easy to return it to normal operation.
It's working as intended. I also have the Smart Strip working in the cabinet, though it took me a few tries to get the sensitivity adjusted right.