1) Start up the game right from the beginning.
2) You will be in a room with a path and many small containers along the side.
3) Look at the ground.
4) In front of some of the containers you may see an Xbox console.
5) This console is a precise model of the limited edition Halo 4 console.
6) There are a few in the room and some can also be found later on in the game.

Here is a video tutorial: