mutiple shock sensors?

It depends on the type of alarm.  If it is a DEI piece then you would cut the blue and green wires and join the blue and green off of  the first shock sensor to either the blue or the green from the alarm and join the blue and green off the second shock and join them to the wire left unconnected from the alarm.  Some DEI alarms have a multiplexed negitive trigger input (blue on the main harness ), what this means is if the shock sensor sends out a ground for less than .3 seconds ( I think that is the time ) it would send a warn away chirp anything longer would result in an instant trigger.  On other alarms you would hook up the power and ground of the shock sensor you are adding  and run the trigger wire/wires to the negative instant trigger wire on the alarms main harness.  The downside of  doing it this way is you would lose warn away in most cases.  Also when hooking up multiple negative triggers to the same wire use diodes to prevent interference between the inputs.