I have the tweak station that came with my Hudy setup kit. However, I rarely use it because I find it easier to untweak my car on scales. It took me a bit to understand tweak but I think I have my head wrapped around it now. Even though a car's ride height might be even left to right, the actual suspension loads can be significantly off. Generally, this happens across the chassis' corners. That is to say [for instance] the left front may have 50g more load than the right front and the right rear may have 50g more load than the left rear even though the ride height is 5.0mm all around. Now the opposite may also be true in a tweaked car. It is also possible to have your suspension loads even left to right but have your ride heights out of whack. This happend to me once when I started using scales and my car was a mess until I figured out what was going on.
Basically, what is happening with a tweaked car is that the chassis is being supported by one set of opposite corners more than the other two opposite corners. Picture this... you have a square table with four legs. You saw 1/16" off the bottom of two opposite corner legs. The table still stands up but it's a bit wobblely. The majority of the tables weight is being supported by the two longer legs with the other two just keeping if from falling over. This is sort of (ok, it's not a perfect anology) what's happeing with a tweaked car. To fix it you need to even your preloads out. You'll want to decrease preload at the corners with more load and increase preload at the corners with less. You CANNOT only do one pair without affecting overall right height. You MUST adjust all four corners to maintain the same right height you started out with.
"Nothing in the world can take the place of persistence. Talent will not; nothing is more common than unsuccessful men with talent. "