I was sent a link to a whole string of posts on the Toyota Territory Off-Roaders Adventure webpage that explained how turn off the seatbelt chime. The directions I followed are below. Even got a tip on the key buzzer which is a project for the weekend. I'm sure this is old news to most of you guys but I'm quite happy with it.
1) Turn the Car 'ON', but do not start the engine (Leave your foot off the brake). Cycle your trip reset knob until it reads ODO. Turn the ignition back off. Wait a couple of seconds.
2) Make sure seat belt is not fastened
3) Turn the ignition back on, do not start the car (Leave you foot off the break) As soon as you see everything light up, press and hold the trip reset knob and do a long 12 second count.
4) Keep your finger on the trip reset knob. Fasten your seat belt, as soon as you fasten your seat belt, you should see the ODO display go from XXXX miles to "b-on". At that time take your finger off the trip reset knob and press it again. It should cycle to "b-off". You should be all set and turn the ignition off and unfasten your seat belt.