If all is working correctly, the light should reset on its own. Some times the valve stems will go into "park" mode and will have to be set at the dealer with a tool like this one > http://www.revolutionsupply.com/VT55-0DB.aspx
Would bet some tire dealers can do it too...
DIAGNOSIS AND TESTING
When diagnosing a tire pressure issue, first check the Tire Pressure Monitoring (TPM) indicator lamp in the instrument cluster during ignition key ON. From the OFF position, turn the key to ON and check the TPM indicator lamp to observe one of the following:
If after 10 seconds the indicator lamp is illuminating continuously (not flashing), proceed to LOW PRESSURE below.
If after 10 seconds the indicator lamp flashes on/off for 75 seconds, then remains on solid, there is a system fault detected. Proceed to SYSTEM FAULT below.
NOTE: Tire pressure may increase from 2 to 6 psi (14 to 41 kPa) during normal driving conditions. Do NOT reduce this normal pressure build up.
NOTE: Tire pressure will vary with temperature by about 1 psi (6.9 kPa) for every 12°F (6.5°C). This means that when the outside temperature decreases, the tire pressure will also decrease. Tire pressure should always be set based on cold inflation tire pressure. For details, (Refer to 22 - Tires and Wheels/Tires - Description)
Check air pressure as necessary in all tires using a known accurate air gauge and adjust to the specification listed on the Tire Inflation Pressure Label (Placard) provided with the vehicle (usually applied to the driver side B-pillar). After adjusting air pressure in a tire on the vehicle, allow approximately two minutes for the message or indicator lamp to go out.
If air pressure in any tire is low, inspect all the tires for leaks. A water “dunk tank�? or other water test may be used to check for a leak around the sensor as long as any water at the valve core is removed once the procedure is completed. The water can be easily expelled from the core area by pushing in on the core for several seconds, allowing escaping air to drive out any moisture. Reinflate the tire as necessary. Always make sure the original (special) valve stem cap is securely installed to keep moisture out of the sensor.
If the indicator lamp is still ON continuously, refer to the appropriate diagnostic information.
After an ignition key ON, if a system fault is detected, a chime will sound, and the TPM indicator (telltale) lamp will flash for 75 seconds, then remain on solid. A system fault can occur by many scenarios, including the following:
Signal interference due to electronic devices or driving next to facilities emitting the same Radio Frequencies as the TPM sensors.
Installing some form of aftermarket window tinting that affects radio wave signals.
Accumulation of snow or ice around the wheels or wheel housings.
Using tire chains on the vehicle.
Using wheels not equipped with TPM sensors.