i need a function that works like pointentity

i have a entity in my game that needs to point at a another entity (like PointEntity()) except the mesh only needs to move it's yaw angle. also, i need it to work like in metal gear solid - you know, the enemy soldiers turn left or right if they aren't pointing directly at solid snake.

does anyone have a function that will tackle this problem that i'm having or am i not being clear enough. any help is appreciated