You will need a jack, a peice of wood with a nail sticking through it, and a measuring tape.
Step one: jack up the front until the tires clear the ground.
Step two: take the peice of wood with the nail in it and hold it so that the tip of the nail is contacting the tire (make sure the peice of wood is on the ground so it can't move). Spin the tire allowing the nail to draw a line. Do this to both tires, trying to get the line as close to the same place on both tires.
Step three: Lower vehicle (make sure the wood with the nail in it isn't under the tire)
Step four: Center the steering wheel, then, using the mesuring tape (an assistant really helps at this point) measure the distance between the lines you just made on the tires. Measure on both the front and back side of the tire. If the measurement is longer in the front than in the back you tires are towed out. If its less they are towed in.
Step five: Adjust as necessary.