http://www.geocities.com/toyota_speed2003/
or
http://www.automotiveforums.com/vbulletin/t172063.html
that one there seems popular
Sequoia 01 - 03
Camry 00 - 01
4Runner 99 - 04
Sienna 99 - 03
Solara 99 - 05
1. Start with the following conditions: you are seated in the vehicle
a. Key is out of the ignition.
b. Drivers door is open, all other doors are closed.
c. Drivers door is unlocked.
2. Insert the key into the ignition (don't turn it) and pull it out.
3. Perform these steps within 40 seconds:
a. cycle the power locks 5 times, evenly spaced and relatively fast.
b. Close, then open the drivers door.
4. Perform these steps within 40 seconds:
a. cycle the power door locks 5 times. (Same as before)
b. Turn the ignition to on, then back to off.
c. Turn the ignition to on, then back to off.
d. Remove the key from the ignition.
5. Within 3 seconds, the power door locks should cycle (automatically) indicating successful entry into programming mode. Return to STEP 1 if the locks do not cycle at this point.
6. Perform these steps within 40 seconds:
a. Press the lock and unlock buttons on the transmitter simultaneously for 1 second.
b. Immediately after letting go of the lock and unlock buttons, press the lock button by itself and hold for 2 seconds. Within 3 seconds, the door locks should cycle once indicating successful programming. If the door locks don't cycle, or cycle twice, repeat steps 6a and 6b - this remote has not been accepted.
c. Repeat steps 6a and 6b for each transmitter that will operate this vehicle, including any old transmitters.
7. Close the driver door.
From that thread on how to do it