How to map 8 motors on pixhawk

First post here. I am coming from ardupilot and have been flying a prototype STOL airframe successfully with ardupilot. This is my first setup with PX4 and im having trouble figuring out how to map my 8 auxiliary channels to the throttle channel. In ardupilot this is controlled by the servo function, but I can’t seem to find the equivalent parameters in PX4. I dont even see a clear way to map the main channel 5 to my right aileron. Does PX4 require me to write a custom mixer for this? It seems like an extravagant solution to a basic problem.

for anyone interested, i wrote a new pass.aux.mix that passes control group 0 yaw and pitch to all 8 aux outputs and it worked. I havent tried throttle yet since i still have to setup the rest of the sensors before arming.