oh I see, I'm not sure , the right ctrl to amiga is standard option in amiberry that we just enable.
It probably is possible with a bit of jiggery pokery :-) I'll look into it.
Do you actually have spare key to use for it on that keyboard? It very minimal :-) (I ask as the key you choose might make a difference to code needed if it's an unusual one) Which system level keymap do you use with it?