JavaScript Gamepad to KM List Variable

Hi. I'm really amazed of the professional possibilities KM can offer.
I'd like to use my Bluetooth gamepad joystick position to move virtual Pro Tool fader instead of using my mouse.
I've made everything working with a USB Jog controler that allow me to move 1 fader at a time but now it's time to make it with 2!

I've found this javascript code but I really don't understand how to get the left and right coordinate in KM.

Can you please help me?

Press button on controller to connect.