There may be some flag in the PCM that has to be set to enable it. Maybe check out TunerPro or Gearhead EFI's website?
But really it's just a second set of shift tables. Back when I was tuning, people would ask me about it all the time, and I would just ask them another question: "Do you want it to shift smooth at light throttle and quick and firm at full throttle?" And the answer would invariably be 'yes!' And so my next question was always "well, that can all be programmed within one table. Why do you need two?
Now, I will grant that there are some instances where you'd want to change shift points and TCC lockup behavior, say for stop-and-go driving vs. not. But that usually takes a lot of trial-and-error tuning that most people aren't up for. It took me weeks to dial in my transmission to shift exactly when and how I wanted it to. You can get into tuning very cheaply now, using a DIY interface USB-TTL interface cable, eehack as your communications software and TunerPro as your tuning software. It's probably best that way as proper tuning for YOUR car is expensive and time-consuming.