I think I can see where you’re coming from, but ‘MIDI learn’ will not enable you to trigger samples, and Renoise needs MIDI notes, not CC messages, to play a sample. This is the same reason why a pad/MPC-style controller will always output MIDI notes per default.
However, if your controller is supported the Duplex Keyboard might be interesting for you (with this tool you can also use CC messages to trigger samples).