Well, for the purposes of my scenario, I really only need the AI to go in one direction, so it doesn't really matter (the human moves via key press, the AI onActivate, though I suppose with the recent changes to onActivate, both could use it).
However, I suppose one could just adjust how far they move over, and make sure there wasn't an overlap so they don't ping pong. So, for example, I teleport the AI units from map 3 to map 0 once they hit a line, and subtract 280 from their location.x during teleportation.
I think as long as you had 2 lines on each map (an exit line further along towards the edge than the entrance line), you could probably achieve a two way direction, though what the AI does once it leaves is, well, the AI. Perhaps coupling this with a goto command that sent it even further along in the correct direction would ensure it kept moving.
I hope I'm explaining myself in a way that makes sense.