What you need:
1) 2 pieces of 10' (that's feet) of 3/4" or 1" metal or PVC conduit
2) Nylon string - at least 50 feet
3) 4 medium size spring clamps
4) 4 jack stands
5) A drill and a selection of bits
6) Tape measure
7) A small metal ruler that goes down to at least 1/16th" and that is at least 6" long
8) Pipe cutter or hack saw
The concept - you are going to make a perfect box around the car using the conduit (up on jack stands) and the string.
Cut each of the conduit to a length of 100" (that's inches). You need to be acurate here. I used a hack saw but I think I pipe cutter would be a better tool.
Measure 12" from each end of the conduit and mark it with a small dot.
Drill a small hole where you made the marks and let the hole continue to through the opposite side of the conduit so you end up with 2 holes - or a total of 8 holes (2 pieces of conduit with 2 holes on each side).
Place the jack stands near all four corners of the car. Put the conduit across the jack stands. At this point you should have a piece of conduit resting on top of the jack stands spanning the width of the car both front and rear. Use the clamps to secure the conduit to the jack stands.
Take the string and feed it through both holes on either side of the front conduit. Tie it in a knot - make sure the string has some abiltity to move around the conduit. take the other end of the stringand pull it down towards the rear piece of conduit. Feed it through both holes, pull it tight, and tie it into a knot. Repeat for the other side.
You should now have a "box" aorund the car... Should look something like this:
Now you need to "square the box" and make sure that the box is even on each wheel. Basically you use a tape measure, or a ruler as described above, and mesaure from the center cap of each wheel out to the string. You will need to slide the conduit around to acheive a perfect box... it needs to be an equal box unless the rear of the car has a different track than the front... if that is the case then the two front measurements should be equal and so should the rears.
Now you are going to measure the tow by measuring from the front side of the rim out to the string and from the rear side. The difference will be the actual toe measurement in inches (or mm depending on what type of ruler you have). By the way your steering wheel should be straight before you start this process!
You can reach under and adjust the front tie rod ends or the rear compensator arm to change the toe.... Here are a couple more pictures.
With this method you can get your toe set to within 1/32" very accurately. The other advantage is that you can take the stuff with you to the track. Oh yeah and it cost me less than $20.
Link to the actual article