External LEDs & Buzzer

I know, that starting somewhere from AP 2.73 this stuff is not supported and can not be activated through MissionPlanner. But I read here
https://github.com/ArduPilot/ardupilot/issues/1082
that “Now four pins (A5-A8) along the left side of the APM2 are always used for external LEDs so you don’t need to set the LED_MODE parameters”.
Unfortunately either that does not works in 3.4 that is the last for APM 2.6 or I’m doing something wrong. Could somebody help me?
I’m just a beginner up to now and have no experience in programming but can try to follow your advices even if they are not as simple.