Set the keyboard on Function/MIDI/KBD & Style.

If the voicelive setup is anything like the Harmony-M, you will find there will be a couple buttons on the voice live that must be pressed simultaneously in order to access the setup feature of the harmonizer. Then it's just a matter of playing a full chord on the keyboard, and the voice live will find the keyboard, set the appropriate channel, which is then saved when you exit the voice live setup feature by pushing those buttons once again.

Gary