GameObject.constantForce  

var other : GameObject;
other.constantForce.relativeForce = Vector3(0, 0, 1);

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
public GameObject other;
void Awake() {
other.constantForce.relativeForce = new Vector3(0, 0, 1);
}
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

public other as GameObject

def Awake():
other.constantForce.relativeForce = Vector3(0, 0, 1)