@zorastro Not sure if u got this sorted already but the connector u want is called a Micro-fit molex (as apposed to the pcie connector which I think might be called Mini-fit, it looks the same but larger). ive attached a pdf diagram of the connector.

@zorastro also make sure you use a usb-ttl cable with the CH340 chipset, other chipsets dont seem to work at all.

@zorastro btw here's a link to the connector I bought and a link to the internal contacts u will also need. 

https://au.element14.com/molex/43025-0608/connector-housing-rcpt-6pos/dp/2779893

https://au.element14.com/molex/43030-0001/contact-socket-20awg-crimp/dp/1462526

@zorastro For anyone not sure about the pinout, this diagram shows pin 1 and 2 and 6 (last circuit), they count upward from left to right same as pcie. This diagram is looking at the face of the connector, not the back where the wires enter. Apply TonyB's pinout diagram to this and you're sorted.