ability to set isomorphic key mapping

[kamkamkamkamkamkamkamkam]

It'd be cool to have an option to set an arbitrary isomorphic key mapping like for example -1 semitones going up vertically and 2 going right horizontally on the (typing) keyboard (Bosanquet-Wilson Layout) here's what it would feel like to use in action with the example given, the values can also be changed under "Isomorphic key mapping"