permanently changing keyboard layout for forth

[Ties Stuij]

I'm trying to permanently change my OFW keyboard layout from spanish to us.

At the moment i can change the keyboard layout with:

select keyboard
set-keyboard ( which defaults to us )

and I guess I have to change the Keyboard ascii map (KA) value in the
spi with values called or used by (set-keyboard) somehow, but this is
wild speculation on my part. I couldn't really figure out the correct
way, and I don't want to totally mess up my keyboard layout by
guessing.

Does someone know the Right Way (or some way less set in stone but
with more or less guaranteed outcome)?

Thanks in advance!
/Ties