just realised if i posted what you need to get it may make things easier for others too...
this is my passport with three stamps - green one at the top is Mexico exit stamp - next one is Belize immigration (entry stamp) - next is Belize temporary import stamp with your bikes information
the piece of white paper behind is the temporary import paperwork, make sure the details are the same and keep them together at all times, to be shown on demand to the police
this is the insurance paperwork, the paperwork/ reciept and the insurance sticker thats supposed to be on your windshield. it was raining the day i came in so i told him i would keep it in my wallet, again needs to be shown on demand by the police - there is a official police checkpoint just outside of Belize city