So just connect pin one and three to the white wire and two and six to the solid color wire on both ends and it should work as long as both ends are half-duplex?

I would think the NICs would sense their own transmissions and declare a local collision?

I'm sorry, I got things mixed up. You're right there would a collision with their own transmission. So there needs to be circuit that cuts offs their RX port while it is transmitting.