@berti2k Sorry, I believe the commands are fixed, not editable. But, I'm not a developer, I can't say that it's impossible, but I can say that it's not something an average user can do.
I don't know what you want to do with the GPIOs, but, see if there's any documentation for that, I know we have something for controllers, for example:
https://wiki.recalbox.com/en/tutorials/controllers/gpio