amblock,
I figured someone who had actually done something similar would reply. However, I have a 2 year old T-2000 that has a very simple method of providing support to the top. It came this way from the tournament I bought it from, I dont' know if it is as factory built or something they did at the tournament to solve a problem. In any case, after adjustment my table rolls true and it is from a time when many were complining about "warped" tops.
Looking inside the table see the two boards that run the length of the table, from goal to goal and form the sides of the ball return. On my table they are particle board placed on edge. On the top edge of each of these boards (about 1/2 inch wide) there is a phillips head wood screw. Nothing special, but the top of the head is flat and about 1/4 inch in diameter. One is placed on the right edge of the ball return hole in the side of the table, the one in the other board is on the left edge.
If you add such, screw them all the way down then back them out until they just touch the bottom of the playing field. Use a lump of putty or piece of wadded up bread to see when it is squishing after you close the top. Don't go too far too fast, I hear you can poke a hole if it is way up. Mine are about 1/2 to 3/4 inch high, but that is just memory and your table may have much closer or completly different dimensions. Once you are close, a quarter turn at a time, some playing and leg leveling in between should get you where you need to be. Just a little support.
Maybe four screws would be even better, two on each side, but mine worked fine and frankly I was damn tired of adjusting just the two by the time I was done.
BillV