Got a link to the part?

Both molex and idc housings should be available with 0.156" spacing to fit pins of that spacing, which i assume is what the boards have

Originally, the wires were just soldered directly to the PCBs. With the new Siegecraft PCBs, you can put .156 header pins on the PCBs, put the wires in appropriate places in the .156 connector housings. Molex would be best, rather than IDC.

It looks like those don't include the pins, so you'll need to order those and solder them into the board, then make up the housings (idc or molex) to mate with them

Yes it is! I did it for Laser Ball last month. Just don't mimic the wiring in my last picture, there was a jumper in the wrong spot.

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Nope, just twist them together, and crimp.

Note that there are different sized pins for different wire gauges. You'll want a larger gauge pin if you're using two wires, otherwise it won't crimp properly.

Yes, .156 pins are available for 18-20 gauge and 22-24. The housing itself is the same.

Twisting the wires together makes it more difficult IMO to crimp, if you can lay both in the pin, you can just crimp. A proper crimp will hold both wires just fine.