To the best of my memeory, Jude liked the headphone mix to be dry and he would start with the main harmony part, then stack that. Move to the next part, perhaps pan the first one off to the side and build the second part. So on and so forth. It does not take long because Jude is really fast and conceiving, executing the parts. Its really fun to do.
We never used a harmonizer at that point mostly because we wanted the foundation tracks to be really in tune and solid. I may have made up a slave reel to do all the parts and then Jude and I would settle on a balance and bounce it back in stereo to the master. The worst thing that could happen would be that we would have to rebalance it at a later stage .
kev