Maybe something like them lighting up on the minimap or screen? It isn't impossible."Hey, but I'm a Jedi and I have the FORCE!!" OK fine, so the AI in the game is going to control your character for the whole game and you are basically going to be a spectator, because you don't ACTUALLY have the Force and there is no way that I can think of that a system that actually emulates the Force is going to work when it comes to lightsaber combat and defenses. You could do an arrow system where it warns you where an attack is coming from I suppose, but the way programers make levels, you can eliminate that all together and just die a few times until you memorize where the baddies are going to spawn from. Either way, it is just going to come down to timing and memorization, because real realism would have the badguys do things that are unexpected and then you would keep getting killed.
Also, Stark I want to here your rant on KoTOR. Because I am a nut.