Prepare a large space in the rear of the room for a cage. Hiding the bunny will require that he not be clearly visible from the door of the room. Empty a large space in the rear of the room, possibly behind a bed or desk.
Use a large or extra large cage for the rabbit. Rabbits need room to move and exercise. Since the rabbit will not be allowed to run free through the dorm for fear of detection, he will need a large cage to permit plenty of movement while the owner is away.
Place a cover over the cage when someone comes to the door. A simple cotton sheet can hide the bunny from others in the room. The bunny will actually enjoy this from time to time, as it gives him security and a dark place.
Clean the cage daily. A smelly cage will give away the bunny in a dorm room. Cover the cage with cedar shavings to hide the smell between cleanings.
Feed and water the rabbit regularly. Besides the health factor, a hungry or thirsty bunny will rattle the cage and create noise.
Give the bunny plenty of chew toys. Occupying the bunny will keep him from chewing through the cage and escaping. This also keeps his teeth from overgrowing.