It does not use a "normal" control set up. The actual thrust is "vectored" by using the joystick.
With the stick in the centre you get vertical lift. Applying power is like pulling up on the collective, the rotating wings bite and you get lift .... but remember the torque reaction so you need to apply some rudder to counteract the tendency for the fuselage to rotate as the power is applied. This is also true in real life.
As you gently ease the stick forward the thrust translates into two axis (actually Z and Y ) and you get some forward movement at the expense of lift. so you need to apply slightly more power to maintain height. (If it helps, think of it as a single engine pointing upwards ).
It is all about sensitive control inputs and lots of practice. The genius behind the coding was Sani, he effectively brought the helicopter into the game within the very real limitations of the game engine. There is a price to pay and that is a loss of stability - hence the speed wobble. This is why it was never possible to achieve effective VTOL behavior ... before you ask

I hope this helps
G