How can I create a new script for turning off the lights?

[CreatID 0]

I'm interested in the post processor automatically adding gcode to the beginning of new print jobs, I'd like to select this as a script in Cura's post procesing plugin.

I pulled the gcode from a prior post: https://ultimaker.com/en/community/23375-how-to-turn-off-or-dim-the-leds-of-the-ultimaker3#reply-162148

How do I add a script that I can select in the Cura interface?