1) In the editor, place a player and an empty Hunter GMG
2) Assign WASD to "Aim Up/Down/Left/Right" in Controls > Vehicle movement
3) Get in as gunner and see how you can control the turret with WASD (3rd person, 1st person and Optics view)
4) Switch to driver's seat via Action menu
5) Enable Toggle Freelook with 2xAlt (or via Esc > Options > Game > Vehicle freelook)
6) Try to drive with WASD