Okay,
So you need to put this script inside each of your buttons. Put it in the "Clicked Script", that will be fine.
You will have to change the output numbers to meet your need. I used 5-8 for this example.
This is a quick way to accomplish what you want.
--Turn on Output 5 turn off Outputs 6, 7, and 8.
local inst = mc.mcGetInstance()
local Output5 = mc.mcSignalGetHandle(inst, mc.OSIG_OUTPUT5)
local Output6 = mc.mcSignalGetHandle(inst, mc.OSIG_OUTPUT6)
local Output7 = mc.mcSignalGetHandle(inst, mc.OSIG_OUTPUT7)
local Output8 = mc.mcSignalGetHandle(inst, mc.OSIG_OUTPUT8)
mc.mcSignalSetState(Output5, 1) --On
mc.mcSignalSetState(Output6, 0) --Off
mc.mcSignalSetState(Output7, 0) --Off
mc.mcSignalSetState(Output8, 0) --Off
You will have to go into each button and change the SetState to 0 or 1 depending on which output you want to turn on with each button.