How do I capture only one instrument from a multiple-instrument recording?
Specify all the instruments that are present in the original audio using the Ensemble Editor, even if you are not interested in knowing what some of the instruments are playing. After having intelliScore generate the MIDI file, open it in your MIDI editor, where you can mute or solo individual instrument tracks and delete the tracks you don't need.
(If you have the Polyphonic Edition of intelliScore and your audio contains multiple instruments, consider upgrading to intelliScore Ensemble Edition. IntelliScore Ensemble is the only product in the world that can listen to audio comprised of several different instruments and convert it to a MIDI file containing the notes played, broken down by instrument. The Ensemble Edition actually listens to the sound of each note and attempts to identify which instrument(s) produced that note. After having intelliScore generate the MIDI file, open it in your MIDI editor, where you can mute or solo individual instrument tracks and delete the tracks you don't need.)