midi-note controlled fx rack

Hi, I'm just wondering if something like this exists (or is possible to build with M4L):

I'd like to be able to trigger the macro knobs of an audio fx rack via midi notes. So all the macro knobs start at 0, but hitting a C1 on some other midi channel for example would turn the first macro knob to whatever the velocity of the midi note is, then releasing the note would bring it back to 0.

Can that be done and if so, has anyone built something similar to that?

Thanks in advance. Alex =]