So you have aftermarket belts? If that is the case there is probably a wire from the old belt that has be grounded or possibly two wires from the old belts that have to be connected together. Basically your just trying to fool it into thinking the belt is secured.
Is it a chime or just a light? I don't remember there being a chime for the belts on my 92. However there was a chime for the key in the ignition which I couldn't stand so I disconnected it. It could be that your chime is the same in which case it's a little box under the drivers side dash that just needs to be unplugged.