I have. My Dad's 2004 UZJ100 did this same thing. To turn off the CEL you put the key in the ignition, turn it to ON (one before start; may be RUN) while holding in the odometer button. Turn ignition to OFF, while holding in the odometer button. Then go back to ON. If you hold in the odometer button the whole time, the CEL will start blinking. Once it does, go back to OFF, and when you start the truck, the CEL should be gone.
This is all from memory, but it's something like that. Hopefully, someone with a FSM can tell you exactly what to do. Or call the dealership, I'm sure they'll tell you.
However, Jonpierre still gave you good advice. If you are throwing a code, and you're not ABSOLUTELY CERTAIN that it is because of a maintenance schedule, you should get it read. You do not want to reset the CEL without checking the codes, because they'll get erased, I believe.
Cheers,
Jay