"shouldn't" be that hard, put multiple collusions(walls - Inb4 someone asks what it is:http://gamedev.stackexchange.com/questions/26501/how-does-a-collision-engine-work ) in the visual wall.
That way, when someone gets cc'ed that ignores pathfinding, he won't be able to go through the collusion
What the invisible wall looks like: http://lh4.ggpht.com/_zoG5sV2wa80/ShficmUyQ-I/AAAAAAAAAEY/iPHshUSh-Z4/s1440/aboveUCwall.jpg
hope it helps :D