The way I set my car up for no tweak is as follows;
Firslty remove the bulkhead tops, top deck, and layshaft cover. This should just leave the lower bulkheads on the car. You can remove the drive train if you want, but it's no biggie.
Then loosen the screws holding the cross braces for the rear bulkheads, and all the lower bulkhead screws in the chassis.
Retighten the lower screws (pinch tight at first) in a cross pattern. When all are pinch tight, tighten harder.
Place the car on a flat plate [important], and retighten the cross braces in the rear bulkheads.
With the car still on the flat plate, take your upper bulkheads, and loosen the shock tower screws, and then place the upper bulkheads on the lower. Tighten the crews in a cross pattern again (also pinch tight first, then harder).
Repeat this for front and rear bulkheads (remembering to place your drivetrain back if you've taken it out
Next do the same for the layshaft brace (x pattern, pinch first, harder 2nd), and then top deck.
Finally, tighten your shock tower screws, applying light
downward pressure to the towers, as this ensure consistancy of placement. Attach your shocks, and then check your tweak, it should be spot on (I usually check mine with an MIP tweak board).
Now thats the long winded method, the key point to follow is regarding the shock towers. They really need to be loose when you reattach the upper bulkheads. Otherwise if you don't realign the uppers into exactly
the same location as before they will induce tweak.
I will admit, that following this method, whilst my car comes out spot-on on the rear, on the front it generally requires half a turn on the LF shock to get right. I have a feeling this is more to do with weight placement than tweak though.
Tweak is something you have to watch with this car though. During the last BIWS meeting I was checking it after every run, and it was usually out... I'm going to look into getting some screw collets to see if I can make it more resistant to it.