I just did this myself! I will try to remember to take picks of my homemade Dreamstick. Honestly, if you can get the string close enough to the rim I would just use a small steel ruler with 32nds degreeing for accuracy. Use fishing line or fine string for most accuracy. I just used contractor string on my jack stands and it was too thick.
Moreover, I bought a Smart Tool from Craftsman online to make my own camber/caster gauge. Another reverse engineer project.
I would actually like to discuss how you are going to set up your jack stands and strings if you want to talk. I got pretty darn close the way I did it. It's all in the initial setup. I want to try MFE's way next time.
I got one of those digital angle of the dangle finders last year (very handy tool for this work).
Here are a few pictures to illustrate my home-brewed version of the Smart Strings toe setting tool:
Scan of one the instruction pages:
Dimensions I chose for the unions:
How it looks mocked up on my turd:
For the unions I used 1"x1"x 1/16" square tubing and the cross arms, hooks and what-not, I used 3/4"x3/4"x1/16". Some lengths of electrical conduit, couplers plus some odds and ends gives you a cheap DIY version of the $400 original.
I was just thinking I should change from the 1/4" SS eye bolts to some nylon screws to save the $1000 brushed on finish.
Jack stands are sooo past tense when you have a set of these babies.