What you coudl do is make small objects such as a radio (If you have the editor upgrade 1.2), and place them in the locations you want to be engaged. Then in the radio's init field put in:
this setpos [getpos this select 0, getpos this select 1, (getpos this select 2) -2]
This will lower the radio under the ground and make in invisible,. Now just throw in a name to each Radio like "R1", and place in a script or trigger using the DoTarget commadn FIRST, THEN then DoFire command afterwards. Good luck.
-=Kilo=-