Load Kontakt, then click the down arrow on the upper left hand corner of the plugin wrapper and select Channels Visible in Mixer. Then Select the Midi Channel you want to use (or Omni). In Midi In Settings choose "Advanced (Midi Channel Configurable Per Generator)".
You'll have to set Kontakt's Layers to accept different midi channels.
I'm not sure that will work but if it doesn't then I don't think it's possible to do in Orion.
Orion 022423-2.png
You can also set the Midi Channel for the piano roll of a Pattern:
Orion 022423-3.png
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