[KBM] Map to custom keys / diacritic character, not just keycode

I would like to use Keyboard Manager to map some shortcuts to keys that currently are accessible only from the "Windows Character Map" application. Specifically I would like to map `AltGr + '` to ``` ` ``` and `AltGr + ì` to `~`.
I know that the Keyboard Manager enables only to map to keyboard keys, but allowing also custom characters would be such a great feature for a programmer.