but unless you "cant" the upper control arm in the slots, I don't see any other adjustment
That is how you do it....
To measure caster in each wheel, we use a caster/camber gauge and turn plates. This tool (caster/camber gauge) attaches to the wheel hub. To check the amount of caster, you need to follow these instructions:
1. Attach the caster/camber gauge to the RF wheel hub first,with the wheels pointed straight ahead and the turn plates zeroed.
2. Turn the steering wheel to the right so the RF wheel has turned exactly 20 degrees.
3. Level the gauge and set the adjustable caster bubble vial so the bubble is at the zero mark on the caster side of the tool.
4. Turn the steering wheel to the left so the RF wheel is turned past straight ahead and ending up at left from straight ahead by 20 degrees.
5. Again, level the gauge, note the location of the bubble on the scale, and record the amount of caster in the RF wheel.
6. While the wheels are still turned left 20 degrees, remove the caster/camber gauge and place it onto the LF wheel hub. Adjust steering so left wheel is at 20 degrees.
7. Level the gauge and set the bubble on the caster gauge to zero.
8. Turn the steering wheel to the right past straight ahead until the LF wheel is turned 20 degrees to the right of straight ahead.
9. Level the gauge and read the caster gauge to see how much caster is in the LF wheel.