?

 function Update() {
if (Input.GetKey(KeyCode.X))
{
   var texture1 : Texture2D;
var texture2 : Texture2D;
var texture3 : Texture2D;

yield WaitForSeconds(1);
renderer.material.mainTexture = texture1;

yield WaitForSeconds(1);
renderer.material.mainTexture = texture2;

yield WaitForSeconds(1);
renderer.material.mainTexture = texture3;

}
}