Although he's not a professional racer, RazorRC creates some entertaining and informative videos so be sure to check out his YouTube Channel. In this video, RazorRC shows his servo installation process on a 4wd buggy and does a great job of describing the small details of the process...
Radio settings (0:30)
Servo horn (2:00)
Servo links / Steering Links (4:30)
Steering rack (6:30)
Radio trim / EPA (7:30)
Video credit to RazorRC. Be sure to subscribe to his channel on YouTube