nitromike,
here's a good method for setting tweak.
1st, set the station so that only one side is on the pivot block, and the chassis (not the other side's wheels) rests on teh stationary part. The goal by doing this is to get each side un-tweaked by itself, to isolate each side. Flip it around and do the other side.
2nd, put the station to full length so that all wheels are on the blocks. Adjust only the side that is on the pivoting part, NOT the opposite corner. I know that sounds contradictory to what you may have heard, but it works. Flip it around and do the other side. After you have done both sides, you should be able to flip the car around back and fourth and have a perfectly tweaked car. Trust me it works.
By the way, you should always have even droop left to right, dont go messing with that to adjust tweak.