how to set rotation / position of an object on trigger?

function OnTriggerEnter(other : Collider)
{
    other.transform.position = Vector3.zero; //set the colliding object's position to 0,0,0
    other.transform.rotation = Quaternion.identity; //set the colliding object's rotation to 0,0,0
    //alternatively, to change the trigger's position/rotation:
    //transform.position = Vector3.zero; //set the collided object's position to 0,0,0
    //transform.rotation = Quaternion.identity; //set the collided object's rotation to 0,0,0
}

You need to edit the Position and Rotation property of the Gameobject Transform. http://unity3d.com/support/documentation/ScriptReference/Transform.html

To change the position use this - http://unity3d.com/support/documentation/ScriptReference/Transform-position.html

For rotation - http://unity3d.com/support/documentation/ScriptReference/Transform-rotation.html