Here's an excellent summary (IMHO) of AFM tuning with LS1edit from Michael Buie. It's recent post from the LS1edit list, but I thought everyone over here should see it also:

Injector Flow Rate Table

Normally, use your Injector Flow Rate (IFR) Table to adjust LTFT's.
Adjust IFR's downward to decrease LTFT (tells the computer the injector is
smaller than what it now believes it is, so more fuel is added, which
compensates for what the computer believes is a lean condition based on O2
Sensor readings, and brings the LTFT adjustment more negative).
Adjust IFR's upward to increase LTFT (opposite of what I said for adjusting
downward).
The intent of the table is to introduce a constant that coincides with the
injector size and the Fuel Pressure.

Theoretically, if you haven't changed the injector or changed your Fuel
Pressure, you should not modify this table. If your LTFT's are out of whack,
you should first look for vacuum leaks and other abnormal situations.
However, modding the car can alter the LTFT's, so you may be justified in
changing them if there are no problems that would induce a shift.

The logic behind zeroing or negating LTFT's is that when you go WOT, LTFT's
will be Zeroed, meaning no additional fuel is being dumped into the engine
at WOT and tuning will be easier. It has been argued that if you can obtain
positive LTFT's of a consistent value, this is just as good, as the value is
predictable, and thus tunable. That argument seems to have merit to me. But,
it has been my experience that when I make LTFT's zero or slightly negative,
my car REALLY wakes up at WOT. It even seems more responsive at part
throttle. But that is MY experience.

MAF Table

This table calibrates the MAF Sensor and should be left stock if your MAF is
stock. Period.
If you get an after-market MAF, in my opinion, they should supply you with
or point you to a means of calibrating for it.

LS1-Edit or a MAFT or whatever could do this.
If you port or remove the screen of your MAF sensor, you have changed it
(and will likely be running lean as a result of the increased airflow).
Assuming one could port the MAF at home in a consistent way, if LTFT's are
positive and MAF related,
Adjust MAF values upward 1% to decrease LTFT's by 1%.
Adjust MAF values downward 1% to increase LTFT's by 1%.

So if you are +10 on your LTFT's, scale the MAF table by a value of 105
(increases the table values by 10%), which will decrease LTFT's
approximately -10. It may take a couple tries.
95 (95% multiplier decreases table values by 5%), which would raise LTFT's
+5.

PE/RPM Table

Increasing the Multiplier (the value in each table entry) adds fuel at WOT.
Decreasing the Multiplier subtracts fuel from what the previous value
supplied.

This is the table to use to tune your A/F ratio on the dyno (which should
decrease or increase O2 Banks 1 and 2 depending on whether you have leaned
or richened the mixture, respectively). O2 Bank readings are one of the
tools you would use to determine if you are running rich or lean at WOT,
relatively speaking, when you are on the track or the street. I've heard
that values of 870 to 930 milliVolts (.870 or .930 volts) are a reasonable
range for NA cars. For Forced induction, I try for no less than 920 mV; 930
mV is safer, still. There are arguments as to why you CAN'T use the O2
sensors to tune. But, everyone does, if they are not on a dyno... they ARE
useful even if they are not terribly accurate from an ABSOLUTE perspective.
The keyword here is RELATIVE. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

That's my understanding of basic tuning the A/F Ratio for optimal
performance.
The experts can chime in here to correct any misperceptions I may have.

Good luck!
Michael Buie