How can I reset the computer on a 2005 Tiburon GT?

If the light is on, resetting does nothing as you have done nothing to fix the car. The problem will still be there and the light will come back on. What was the code?

If you are talking about the monitors, it is a very specific way of driving a car to run the monitors. If your light was on, the monitor will not run for that system until the issue is resolved.

Roy

If you're talking about setting the monitors-see below

Perform this drive cycle until the required number of readiness codes are set as required by your State test.
Fig. 2: Hyundai Drive Cycle To Set Readiness Codes - Except With Delphi EMS
Courtesy of HYUNDAI MOTOR CO.
DRIVE SCHEDULE NOTES:
Coolant needs to be within 0 to 40°C (0 to 104°F) at start.
Fuel level must be above 15 percent.
When decelerating from 50-55 mph, there needs to be at least 5 seconds of fuel cut-off; its best to close throttle as soon as possible for 5 seconds to assure decel fuel cutoff occurs.
Try to maintain constant throttle as much as possible during the steady state speed portions of the drive cycle.
CAUTIONS:
This schedule is best driven on a dyno if available, otherwise find the best road with least traffic.
Obey speed limits and drive safely.
If you lose the schedule due to traffic, attempt to get back to it when conditions are safe to do so.
Keep your eye on the road and avoid looking at the schedule constantly; its best to have a passenger describe the schedule to you while driving.