nah! there's a simple way, just use waypoints
unless you want to make some funky curvy path you will probably just have straight paths and turns.
So you just have to now when and where to turn.
You place some sprites with an instance variable called direction
Sprite.direction equal either 0,90,180 or -90
you probably have an entry point for your ennemies and a starting direction, you make them move in this direction and when they overlap the sprite you just change the angle of movement to the angle of Sprite.direction.