It's pretty easy, really. I used two pieces of angle iron, a screwdriver, and a dial indicator on a magnetic base, although you can do something similar cheaper.
The angle needs to be 2 feet long or more, so you can clamp it to a work surface and have enough hanging over for the wheel to spin freely. Cut a notch in one end of each, so the axle will have something to sit in. If you have a steel worktop you can get a dial indicator and magnetic base from Harbor Freight for about $20. If not... you can buy the indicator and base anyway, and remove the post from the base and drill a hole in the angle at a location that would be about where the base should be.
You'll want to take measurements around the rim and mark the high spots. When you do the radial, or "hop" you want to tighten the high side, and loosen the low side. When you do the axial, or side to side, you want to loosen the high side and tighten the low side.
If you don't have a spoke wrench, and the tire is off the rim, remove the rim strip and you can use a screwdriver on the spoke nipples.
