modified node structures are generally made to fit the truck (if you hit K ingame you can see the structure as green lines) and have accurate suspension travel.
you have to hit Y ingame inorder to bring the ingame chatline up.
Practice, practice, practice. The only thing I can really say is to lead the corners with front steering, swing the rear steer until the truck starts to slide, then carrying the slide through the corner. You will have to play around until you feel comfortable with pitching the truck into a corner and knowing how it is going to react.