Aux PWM Passthrough from RC Channel

Using Plane how do I map say SBUS Input Channel 10 to AUX1 PWM? I know this must be a basic question. I do not want to run a PWB servo cable from the RC receiver but want to do it from the autopilot Aux pins as it is much shorter.

I am not seeing how I do this with RCx_Option in the documentation here

I do not see an option that corresponds to the AUX Pin? What am I missing?

Many thanks if anyone could enlighten me.

It’s a servo function:
Aux1 = channel 9 (on a Pixhawk), so set servo9_function = 60

Thx James. Appreciate it.

No worries. It’s hard to keep track of the 1000-odd params!