Adding PWM output to Flywoo F745 by changing buzzer pin in hwdef file

Hi I’m pretty new to working with Arducopter, so sorry if this is an obvious question, but I couldn’t find the answer anywhere else. I’m trying to change the buzzer pin on the Flywoo F745 to a PWM output pin. I believe this can be done by editing the hwdef file found here libraries/AP_HAL_ChibiOS/hwdef/FlywooF745/hwdef.dat, however I’m not sure how to make changes to this file that would be reflected in the firmware. This post here makes reference to doing something in the same vein as what I am attempting, but they don’t talk about what they did after making the changes. If anyone could point me in the right direction it would be greatly appreciated. Thank you!