New rover wheelconcept

Hello, I have a rover with 6 (individual) moving wheels (see Rover parcours in VR to be played on the Maker Faire Eindhoven 25 and 26 september - YouTube ) . This means 12 servos (2 per wheel, 1 servo for turning the wheel and another for slewing).
I developed the code to drive all 12 servo’s simultaniously given the intended translation speed (forward, sideways) and rotation speed (so 3 inputs - to 12 outputs).

I want to use PX4 to drive it.

Question: How to go about making a mixer for this? (If a mixer would be the right choice)

Also: I have a hex cube black with enough outputs, but 8 are “main” and others “aux”. Does that matter, can I drive servos via the “aux”.