Just an idea, This might be really hard, but bear with me here, and its just an idea. Hoping somebody can help me out.

1. A material like a bright orange emissive that would have an black arrow walking through the material and follows the enemy, and yourself as player.

2. Lets say I have one small 32x 32x 32x brush walking through the middle of the CSG of my floor, through the entire map, and on whatever CSG/Floor the player or the enemy is on,
The arrow will track him down at spawn, and will guide you to meet another arrow where the enemy is, in the map (Sort of like an enemy pointing device)
Although, the arrow does not point into a direction. It follows only the quickest path guide.

3. So summarized:
The material must: 

> Guide the player, to the enemy, when he is spawned
> Same for the enemy (enemies) above
> The speed of the arrow guiding you must be equal to walk speed, and increase when wall jump for example, or "speedjump" to a location if fast moving (Lifts, Jumppads)
> The arrow must disappear when the player dies, and reappear on the CSG of the floor where the player spawns, only to restart the cycle.

Sounds more something for UDK.. I know.. but if its possible.. I would really like to know ^^