if ($did(1).state) { command1 } | else { command2 }
This would trigger command 2 if the box is checked, command1 if it is unchecked. If it's unchecked, the $did(1).state will return 0, which will make mIRC interpret the if statement to be false.
DALnet #Helpdesk I hear and I forget. I see and I remember. I do and I understand. -Confucius