Movement using the w,s,a and d keys would likely be possible through use of the keyboard template script,
here. Using that and some setvelocity manipulation, movement should be easy.
Pitching with the mouse would also be easy (rotating in the x/y plane) via getdir commands. Yaw may be more difficult, however. Finally, firing the tank would be possible via a "fired" eventhandler attached to the player; but for this you would need a weapon that prefarably a.) had unlimited ammo, and b.) was unlikely to injure the player if he fired. For this you could look into the 'combatstrokegun' weapon or whatever it's called.
So, yes, this sounds perfectly possible.