I think it should work. When you set the opponents town it was given a player number. Looking through the scripting tool with the modding tools there is a part that states "Gets the players creature. (get player 2 creature)" The bit in brackets is the actual code. Could you use this in conjunction with the next statement "CreatureArray[CLION] = create DUMB_CREATURE CREATURE_TYPE_LION at {1575.928, 111.473, 838.692} using only alignment good neutral" to create the set creature "CREATURE_TYPE_LION" and its exact position i.e. its creature pen. Then when you play the level your enemy should have a creature in the location you want it in.
Haven't tried this personally but the logic seems there for it to work.
The codes were in the STATEMENTS then OBJECTS and then scroll down to CREATURE OBJECTS.