If the triggers are made of geometric shapes (like an area covering a door entrance or something) then our DLL with the "no response" setting for the object would be perfect.
Essentially, in our DLL, you can hide the object, applly no response collisions, and then scan for contact with this hotzone object, and it will not physically move your object when you run into it.
If it's a simple massless marker (as in waypoints like BatVink said) then you can just use some distance math to take care of it.
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http://www.nuclearglory.com