Hi @ants_b, welcome to the Community! You can definitely customize the FLX4 MIDI mapping and change one of the existing Performance Pad modes to control Neural Mix. Please refer to the FAQs below on MIDI mapping in djay and let me know if you have any further questions:
Also, I describe in more detail in this topic: Djay Pro / IPad / DDJ FLX 4 - #11 by Slak_Jaw
