Here you go, directly from the manual.

One time disable - Anytime the safety belt is buckled and then unbuckled during an ignition ON cycle, Belt Minder will be disabled for that ignition cycle only.

Deactivating/activating the belt minder feature -

Read steps 1 - 9 thoroughly before proceeding with the deactivation/activation programming procedure.
The Belt Minder feature can be deactivated/activated by performing the following procedure: Before following the procedure, make sure that:
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the parking brake is set
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the gearshift is in P (Park) (automatic transmission).
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the ignition switch is in the OFF position
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all vehicle doors are closed
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the driver’s safety belt is unbuckled
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the park lamps/headlamps are in OFF position (If vehicle is equipped with Auto lamps, this will not affect the procedure.)To reduce the risk of injury, do not deactivate/activate the Belt Minder feature while driving the vehicle.

1. Turn the ignition switch to the RUN (or ON) position. (DO NOTSTART THE ENGINE)

2. Wait until the safety belt warning light turns off. (Approximately 1–2minutes)
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Steps 3–5 must be completed within 60 seconds or the procedure will have to be repeated.

3. Buckle then unbuckle the safety belt three times, ending with the safety belt unbuckled. This can be done before or during Belt Minder warning activation.
4. Turn on the park lamps/head lamps, turn off the park lamps/headlamps.
5. Buckle then unbuckle the safety belt three times, ending with the safety belt unbuckled.
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After step 5 the safety belt warning light will be turned on for threeseconds.6. Within seven seconds of the safety belt warning light turning off, buckle then unbuckle the safety belt.
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This will disable Belt Minder if it is currently enabled, or enable Belt Minder if it is currently disabled.7. Confirmation of disabling Belt Minder is provided by flashing the safety belt warning light four times per second for three seconds.8. Confirmation of enabling Belt Minder is provided by flashing the safety belt warning light four times per second for three seconds, followed by three seconds with the safety belt warning light off, then followed by flashing the safety belt warning light four times per second for three seconds again.9. After receiving confirmation, the deactivation/activation procedure is complete.