I started by adjusting the entire amount of the LTRIMs based on histograms. It started getting me REAL close to 0, but not quite dead-on. First though, I did not give it enough time to relearn, which the computer will need to do. Second, the next time I tune using this (after my LTRIMs are relearned) I am going to subtract the LTRIM and 1 (so if the LTRIM is 10, subtract 11) for positives, and the LTRIM minus one for negatives (if LTRIM is -10, add 9), that way I can shoot slightly rich. The VE table won't move, but you are going to move the VE table with the LTRIMs. I have done this to fix low-end drivability so far without using the 60/80/90 method on the VE table. It is much more accurate. What I have been seeing is that a lot of the table after the cam is near 85% of the original value at low vacuum/RPM (based on 90% of my IFR table...so now it is going to change, more than likely towards 75%).
I actually saw mine move in one drive about 1/2 to 2/3 the distance I changed. I don't know exactly how far it would have gone. One thing I have also been pondering is that adjacent cells will affect any surrounding, so it will take awhile. If you overshoot, just go back and add a little back in.