Fish I think this is not what the guy meant, he wanted to make placing mines a task for player (and goal that is trigered when the mines are placed by the *player*).
It's easy to do, I did it for some of my scenarios and I know it works.
Use the detection goal, so that when a certain object (in this case mine) appears on the given spot, the goal is triggered. I think mines (as objects in the editor) are under "Civilian" group (can be confusing).
Gee, I realize now my mission editor skillz got rusty, I can't even remember the names of certain procedures
Let me know if you still have problems, I'll try to be more specific.
Oleg