Wireless endoscopic video capsules are becoming largely used today for non-invasive explorations of the digestive tube. Traditional types of such capsules present a major drawback: their motion can not be controlled, since they proceed by means of the visceral peristalsis only. In order to enable a wireless control of their motion, this paper describes a new concept based on the use of external magnetic fields. The proposed technique exploits magnetic shells to be applied to traditional capsules prior to their use. The shells are capable of interacting with an imposed external magnetic field, providing a means to control the capsule movement and orientation. This solution is readily and cheaply applicable to any commercial endoscopic capsule, avoiding internal modifications. The paper reports results of preliminary bench tests. Prototype elastic shells made of a silicone elastomer mixed with magnetic particles were fabricated and tested with the Given Imaging M2A capsule in simplified experimental conditions. These tests permitted to demonstrate translations, rotations and roto-translations of the capsule/shell complex onto pieces of bovine tissues.