>>11957250
An Xbox360 controller? Weren't those just standard USB? If you want to use that you can just plug it into any actual USB port on the MiSTer, preferably one on the hub. (Obviously, not the SNAC port or the two power-only ports)

I am using this for most games I play on MiSTer, but I have SNAC adapters for some of the cores that I use instead:
https://www.8bitdo.com/ultimate-2c-wired-controller/

There are probably better options though depending how much you want to spend, I was able to get that one pretty cheap