It depends on when you were in high school I think. If it was more than a couple of years ago, his laptop was probably just doing data collection, not actually reprogramming anything.
Different tools are available, using the slow ALDL data stream (updates at ~1.5 seconds per frame) you can get several laptop based collection tools (TurboLink, Win ALDL). Many many of the Buick crowd buy a Scanmaster which plugs into the serial port and leave it mounted in the car permanently. Its a little black box that I mount discreetly below my dash.
Direct Scan is available and plugs into a factory service port in the ECM and gives up to 18 frames per second. This is the only way to go if you are really into tuning.
For programming you can download a number of tools online some free some not. You can modify the vehicle binary using a hex editor for brute force stuff. You will need a PROM reader/programmer and a UV eraser to actually modify the chip. I bought PROMs for $4 each.
There are PROM emulators available for on the fly tuning, they plug in where the PROM goes and are controlled by a laptop. You do your tuning live and dump binary images into the emulator with the car running allowing instant changes. When done, burn the final tune into a chip. You probably don't want to leave an emulator in all the time for normal driving.
If you have specific questions I can come up with some links and such. Other people on this board will have good ideas too.
