It is possible to do this using the Input Transformer by transforming notes.
For example, here’s an image and a preset file for one I made for harmonic minor.
Unzip this file and place it in your User Settings folder at
%appdata%\Steinberg\Cubase 11_64\Presets\Input Transformer
and restart Cubase, then open the Input Transformer on a midi track and load the preset.
white keys mapped to harmonic minor.zip (753 Bytes)