Record the notes you want to "sing" on a MIDI trck
Record yourself singing the parts

Use Harmonizer and pay attention to the options on how it is going to harmonize. One of them is to use a MIDI track instead of chords. Once you get how to make one work, you'll be doing three at a time pretty quickly.
Experiment; it's rather intuitive if a little time is invested. That's how I learned what it does.
I don't know of any videos, but there may be some.

Tip;
Play the MIDI notes in the correct range and timing. Mid-low if you desire a baritone voice .. mid-upper for alto .. etc. That's part of the experimenting; finding the right range for the male/female selection and singing it in time with the MIDI so it doesn't jump suddenly or "warble". Which means playing the MIDI as if you were singing it (timing wise) so it naturally tunes the voice, as opposed to starting after the vocal part, which will make it jump to the new note.
Lean toward the early side.

Last edited by rharv; 04/20/12 04:00 PM.
I do not work here, but the benefits are still awesome
Make your sound your own!