I don't think flying helicopters in DC is too hard either (I'm also a keyboard/mouse user btw). The trick to learning it is to start slowly.
(for keyboard control: )
Press the 'up' key (or 'W') to start lifting, and don't press anything else. When you let go, you should float back down quite nicely.
Next, press the left or right key ('A' or 'D') once while your in the air. you should start turning. Press the opposite and you should stop turning (or almost).
Now you'll move with the mouse, and this is the tricky part:
move your mouse slowly forward
a little bit. (you'll tilt forward, and move in that direction). To stop moving, move your mouse back about the same distance
slowly. Never over-compensate or you'll crash.
Take it easy and just move the mouse a bit in any direction and watch what happens, move in the opposite direction to counter the movement, but stop moving well before "you're there"; the movement will still go on for a while hopefully stopping just where you'd want it to.
With practice (start a one person game) you'll be flying and capturing spawn points with the helo in no-time. (that is until you get a decent plane-opponent and he'll blast you out of the sky
)