You'd be looking for achromatic diopter lenses, which let you get the camera extremely close. They come in various powers, such as +1, +2, +3, etc., on up to about +10 for the most magnified. You will have extraordinarily shallow depth of field (as in, fractions of a millimeter) and you'll have to get the camera extremely close to the subject.
Century makes a line of high-quality achromats for the DVX, but they're on the more expensive side too. Nikon makes the 5T and 6T, which are inexpensive and good quality diopter lenses, they're about $50 each, but you need a step-down ring to use 'em. Some people are using the Hoya +10, it's not expensive and it's high-power too.
