To my knowledge, trigger zones will always be active, checking to see if the player is within or not, but there is a way to do what you want. It just depends on how your level is set up.
This is just an example so you get my meaning.
:state=0,plrwithinzone:state=1
When the player steps in the zone the sequence is started...
:state=1,plrdistfurther=60:state=2
The player passes through the zone and the trap is set...
:state=2,plrwithinzone:some surprises...
The second time he enters the zone you get him...
Best.
I'm sorry, my answers are limited. You must ask the right question.
