Toe is easy to do with a tape measure and camber can be guessed at pretty well with a straight edge and bubble level but caster is the tough one. At least on a IFS. Caster wouldn't be too hard with a straight axle I suppose.
I think a person could design a fixture that measured caster directly off the knuckle but it would take some clever thinking.
With a spool the car is already hard to turn, so dialing in as much caster as you can just makes it ride better down the track.
