Disconnect one endlink on each sway bar. The job of a sway bar is to resist dynamic weight transfer when the chassis is loaded. Disconnecting one endlink from each bar will allow the chassis to move freely as you adjust weights. (If you don't disconnect the sway bars prior to adjusting the crossweights, you'll put the bars in a state of tension, where they're pre-loaded. This will do all sorts of wacky things to the way the car handles.) After the crossweights are set, the endlinks should be adjusted so the bolts can be easily re-inserted. Obviously, adjustable endlinks are needed to achieve this.
It's now time to roll the car up onto the scales and determine its current numbers.
To get the true corner weights, the four scales need to be situated on a flat, level surface. One way to check this is by stretching strings, in the form of an X, between the left front and right rear scales, and between the right front and left rear scales. Adjust scale height until the strings just touch in the middle. An easy way to adjust scale height is with square linoleum tiles. LG's scales have levelers built in and had been pre-leveled.
D6C's corner weights were off by a lot. The LF/RR showed 52.8 percent, which is way outside of acceptable. Of course, you're trying to achieve a perfect 50 percent. If you're adjusting a car that still has leaf springs, anything inside 51 percent is considered pretty good. Coilover cars can generally get to 50 percent, as there are no rubber bumpers to contend with.
Set your desired front ride height and then adjust rear ride height to achieve a 3/8- to 3/4-inch rake. Rake is important in order to avoid running into lift at high speeds. The idea is to minimize the amount of air going under the car. Measure rake at the jack points between the wheels. Choosing ride height is a personal preference. Low is good, but if you go too low, you'll run out of suspension travel (assuming stock springs and shocks are used). Again, coilover-equipped cars generally don't have this issue. Be sure the front ride height is equal from left to right prior to setting rake.