Nope.. This can't be scripted. What notes correspond to what keyboard keys is hard coded into Renoise.
If Taktik wanted, this could add it as one more option. Another thing is that it is useful.
(If you mean temporarily having focus on another window catching/forwarding data, that's such a bad idea with crappy implications that it's not even worth suggesting)
Over and out.
Obviously I mean this. It is not nonsense, it depends on what you use it for. In fact, I already have a tool with this approach (with another order). To shoot notes is perfectly feasible. Another thing is that you do not like having to focus the tool to shoot. As I pointed out before, the only limitation here (aside from selecting the tool), is that there is no "the release note" for the alphanumeric keyboard keys and that is a limitation of the API that can be solved in the future.
A practical example is a tool with that distribution, but that only triggers the notes, through OSC, and a slider to control the speed with the mouse. In particular cases they could work.
Anyway, it is better to use a MIDI device for these things, and forget about so many complications.