Yes you can use it. I believe it's positioned 1/3 (or more) from the stern. See it as a joystick, you can move it 360 degrees and the more you push the stick the more trottle it gives. It doenst have effect when the ships speed is too high (same as the bowthruster), so you'll only notice when the ship is stopped or at a very low speed. Once you get the hang of it, you can get the vessel anywhere you like in combination witht the bowthruster and the 2 main engines.
When you hold the mouse cursor on it, you see 3 different rings. Whe you move the inner ring (blue one) you change the direction, when you move the red and green ring you will set the trottle.
