You don't need to worry about that "ring" if you don't have a shielded cable. I seem to recall that it didn't even attach to anything metal on the monitor anyway (weird).
If you wish to make a harness yourself, the cable side connector for PC level signals (0.7Vpp into 75 ohms) is a 6 position Molex SPOX 2.5mm connector p/n 50-37-5063 (housing) 08-70-1040 (crimp terminal). You can buy these parts at Digi-Key or Mouser easily.