Modify Terrain Data in Unity3D during Runtime

How do you change the Pixel Error, Base Map Distance, Cast Shadows, Tree Distance and other settings from runtime, not in inspector using UnityScript or C#?

It's relatively easy when you reference the Component on Terrain. This script should work:

Terrain.activeTerrain.GetComponent.<Terrain>().heightmapPixelError = 200;

for(var gameObj : Terrain in GameObject.FindObjectsOfType(Terrain)) {

        gameObj.GetComponent.<Terrain>().heightmapPixelError = 200;

        gameObj.GetComponent.<Terrain>().basemapDistance = 200;

        gameObj.GetComponent.<Terrain>().castShadows = false;

        gameObj.GetComponent.<Terrain>().treeDistance = 500;

        gameObj.GetComponent.<Terrain>().detailObjectDistance = 25;

      }