showMap true (or false)
works just fine in the mission editor, that's what I tested. ;D I think you've got it back to front LCD .... you use 1/0 in the description.ext and true/false in the ME.
The map actually disappears while you're looking at it, which is pretty cool. You could make a nice "pissed as a fart" script where the map switched on and off every second or so. Now that would be freaky.
macguba 1 : LCD 0