// Set the controller radius to 0.3
    var controller : CharacterController;
    controller = GetComponent(CharacterController);
    controller.radius = 0.3;

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    public CharacterController controller;
    void Example() {
        controller = GetComponent<CharacterController>();
        controller.radius = 0.3F;
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    public controller as CharacterController

    def Example():
        controller = GetComponent[of CharacterController]()
        controller.radius = 0.3F