How can I set up a keyboard to work as a controller?

I have a controller but it's too small and I have to keep using the octave shift button. I also have an Alesis 1622 Quadrasynth + Piano. How can I set it up so that it triggers virtual instruments and works like a controller.
 
It would be cool if I could also switch back and forth from controller mode to the internal sounds.
 
Thanks - rev