I have put my changes in a fork at:
You might want to check if I have followed the right conventions.
I have it in monochrome at the moment, but could change it to colour. I have never used an Apple One so don't know what it is supposed to look like.
The CTS signal currently maps onto a random pin as the BlackIce II uart does not support it. I could remove that. Anyway, PS/2 keyboard use is currently hard-coded in.
The two BlackIce buttons are used for reset and clear screen.
Led usage is currently a bit random - I was just using them for diagnostics.
Let me know if you want me to issue a pull request.