If you want to use with 220V then the two far ends are the ones you need. So I do suppose that the center ones are for 110v.
The thing is that you wont be able to find the particular 4 pin connector for a diy cable , and any other solution seems not reliable. So instead , I'd use a 24V 3+Amp power supply externally and replace the integrated one. That will reduce the thermal load as well.