1. Cut the existing Seatalk cable. First make sure the instruments are switched off!!
2. Remove insulation
3. Use similar shielded cable (gray cable in picture) to connect ST-bus to the multiplexer.
4. Combine the original and the new cable as shown. Use commonly available screw terminal strip and small plastic box for protection. Glue the terminal strip to the bottom of the box with a little superglue.
5. The finished product. Cost: $3.00