Viewing channels on scope

Hello all.

I am using a Logitech F310 joystick with mission planner and a Pixhawk.
the Pixhawk is configured to work as a Rover.

I have configured one of the sticks for roll & Throttle, and I can view the PWM changing on the Scope, on main out #1, #3, which is just fine.

I would like to use another button or stick at F310 as a trigger or as another PWM.

Is there a way to accomplish that ?

Thank you,