https://github.com/niuus/Snes9xRX/blob/master/README.md
I read that already, couldn't get it to work. Are you talking about this
USB CONTROLLERS
To enable the Speedlink Hornet Gamepad or the Xbox 360 (wired) controller, there are two ways available:
Before loading Snes9x RX, connect your Xbox 360 wired controller. If the other USB port is populated (example: USB HDD, flash drive, DualShock 3) it should work the moment you start a game. For manual detection, when you're at the main screen (Choose Game), click on the emulator logo at the corner and check the status info at the bottom, to confirm detection. The same can be achieved by opening the Credits section inside "Settings".
Remember, the controller only works when in-game. You can swap your player/port number by simply pressing on the Xbox Guide button.
To enable the DualShock 3 (wired) controller, press and hold both minus (-) and plus (+) buttons in sequence, then release. You can do this in the Wiimote, or even the Wii U Pro Controller. The DS3 led #1 should light up once, and then the four leds. After that, press the PS button, it should be enabled for in-game use by now. You can do this before loading any game, for example.