LocoNet is flat unshielded 6 conductor telephone wire with RJ12 6P6C connectors. Digitrax sells a kit to make the cables. I’ve actually got a lot of left over cable and connectors. Are you located in the U.S.? I could make you a cable. What length do you need?
when you're makin your cables, pay close attention to the orientation of the individual wires in the connector. If you get em backward, you can end up with shorts in your system that are very hard to find.