A 4 wire motor is bipolar only. If you test for continuity between the four wires you'll find that there are two pairs.
Per the specs if you supply this with 2.4V then it will consume its maximum 2.0A (and thus you know the coils have a resistance of R = V/I or 2.4 / 2 = 1.2 ohms). This is not normal to drive them at this low voltage, however; typically you'll run this somewhere between 12V-40V for better speed. Using it at those higher voltages requires what is known as a "chopper" (or "current limiting") driver to keep the amperage at 2A.
So here's what you want to look for:
1) A power supply, probably 12V would be a good place to start but don't go looking for a power supply before you can see what the stepper performance is like with any ol' thing you can find lying around the house.
2) A motor driver like http://www.pololu.com/catalog/product/1182
3) A microcontroller (Arduino) to control the "step" and "dir" pins on the motor driver.