I've just spent a good while trying to make this happen, but I'm just stuck on the basic hello world example.
I've navigated to /usr/share/X11/xkb/symbols
and edited the us file (since I use a standard us keyboard) and changed the first instance of
key <AC08> { [ k, K ] };
into
key <AC08> { [ k, K, A ] };
I also deleted the .xkm files in /var/lib/xkb and rebooted. According to
I should now expect to see a capital A upon rightalt+k, but I get nothing.