Handling servos in ArduCopter.cpp

Hello everyone.
I am a developer with many years of experience but a complete newbie in Ardupilot.
I’m trying to modify the ArduCopte.cpp controller to add the servo handling functionality just as ArduPlane.cpp does, but I’m having problems.
I would appreciate any help, trick or link to any manual or blog that explains how the code works so that I can understand it so I can make the modifications.
Many thanks.