Set RC10_FUNCTION param in code

hi guys
I want to set RC10_FUNCTION to landing gear in code and i can’t find where should i change.
any suggestion a bout this?

I personally edit the parameters directly (in the ‘Full Parameter list’ in Mission Planner in case you didn’t know). The wiki really does tell it all.

One note which may help following the wiki - make sure you get the values for LGR_SERVO_DEPLOY and LGR_SERVO_RETRACT the right way round. Not all gear servos work the same way! Many people mix these values up. DEPLOY is the PWM value when the gear is down, and RETRACT is up. Also, make sure the PWM values you specify are more than those which are required to make the gear trigger I.e. if the trigger point for gear up is 1875pwm, then set it to 1950-2000. And again for gear down it could be 1100, so set say 1000. Just to make sure you are giving it more than required to be sure that actuation will happen.

I would like to add - if you want to be able to manually control the landing gear from an RC channel input (as well as the settings in the wiki) - then also set the CHn_OPT=29 (choices are for n to be 7-12)