Just bringing this topic back up after I did a search on the forum for a way to turn of the seat belt chime. No one have any clue?
In my last car (Range Rover) you could put the car in "program mode" (push ignition button not pressing brake so everything comes on but engine doesn't start turning) and then put the seat belt in and take it back out again 8 times. After the 8th time you hear a chime and the seatbelt chime is disabled. You can do the same again to engage the seat belt chime again.
For the Range Rover I also found this info on a forum, where another member had figured this out (or got the info via dealer, connection at importer or what ever).
If anyone has any info on this for the Maserati, please do share!