Actually, multiple keys for different velocities is okay( Tab, Alt, ctrl are available), but you'll end up having few fingers left to play...
, since you have to hold them down as you play. I know the Up/Down Arrow keys change velocity via the Volume controller knob, but it ONLY changes when you're NOT playing. My idea is to make it so the Arrow Keys work WHILE you play, and just tie/bind them to velocity itself and NOT necessarily the Volume knob, so the Volume controller could be freed for other use. This way, at least you'll only need to use a max of two fingers (one for up arrow, another for down), and, of course, your left hand will be free to use. Problem is, one hand will be stuck on those Arrow keys, but ONLY for places where a ramp up or down in velocity is needed. It's a little clumsy, maybe, but if anyone knows of something better, i'm all ears.....