I actually did think about that process but most if not all audio to midi converters just convert the multi key audio piece to one assignable midi note instead of the corresponding key.
Like the
KT Drumtrigger for example, that I used to use for individual drums (kick, snare, tom etc) which works in this case because the Kick usually follows on C1 on the keyboard.
I stopped this because I didn't like working with midi in place of a real instrument.
Perhaps I haven't found one that does do multi-key midi mapping?
EDIT: I stand corrected:
http://www.akoff.com/music-composer.html#samples
