We chopped off the TRS without any ceremony and then stripped back each side of the cable. This exposes a pair of conductors, side by side. They are insulated by enamel, which poses the first problem. I was loathe to scrape or sand these tiny conductors, but what worked was to dip them each in rosin flux, then tin them using a soldering iron with a good sized drop of hot solder. Between the flux and the heat, the enamel cooked right off and the wire tinned nicely. The rest of the assembly was straightforward, although we added a third wire, about 1.5 inches long to provide a triangular cross section for the Neutrik strain relief to grip onto. We captured this with some heat shrink tubing, which yielded what looks like a good assembly.
The notes in the following were very helpful:
Tom's Electronics pages / tom@mmto.org