Can UI elements be added over over player/monsters heads?

[Lodur]

Is it possible with the API to replace the health bar over enemy player/monster heads with a custom UI element?

I'm thinking about an addon to mark Healers, Vamps, Weres, Low Max HP, etc... players with icons over there heads...

I known every I need for this except if I can display it over the enemy's head on screen.

Thanks