Adding a single keycode to the existing XKB configuration

I have a MECHREV laptop, /sys/class/dmi/id/product_name "Jiaolong Series GM5ZG0O". Its keyboard has a button for toggling trackpad on/off. However this key emits keycode 93 which is not mapped to anything in /usr/share/X11/xkb/keycodes/evdev which is the auto-configuration Xorg chooses. I don't want to modify this file because I'm going to lose these changes when xkeyboard-config gets updated by the package manager. However I would like my changes to be permanent and system-wide. Ideally i'd like to have additional local configuration, something like this: /etc/X11/xkb/keycodes/touchpadtoggle

default xkb_keycodes "touchpadtoggle" {
     = 93;
};

/etc/X11/xorg.conf.d/touchpadtoggle.conf

Section "InputClass"
    Identifier "Touchpad Toggle Key"
    MatchIsKeyboard "on"
    MatchProduct "AT Translated"
    Option "XkbKeycodes" "+touchpadtoggle"
EndSection

This doesn't work, probably for multiple reasons: - Xorg does not seem to look in /etc/X11/xkb for configurations - The "+touchpadtoggle" syntax is probably invalid Is this at all possible? Or is there another way to add a single key to the keymap without creating my own layout from scratch?