How to add custom Keycode

Hi, I would like to ask if anybody knows how to add custom Keycode in Phaser 2?

I tried using this code in game.js but it’s not working. There is a red button in remote control for android TV which the keycode is 183 and it was not listed in Phaser 2 Keycode List

    Phaser.KeyCode = {
        REDBUTTON: 183,
    };

    var REDBUTTON = game.input.keyboard.addKey(Phaser.KeyCode.REDBUTTON);
    REDBUTTON.onDown.add(this.startSpin, this);