I'm not sure where you could find the others. Unfortunately World Leaders shut its doors a few years ago, with a lot of people moving over to Titmouse. The finalized historical figures were all rendered in Flash so that they could be animated walking around on the studio's title card.
As for the two that I made, they were never prepped for animation. There's no real trick to how I made them, so I never bothered coming up with a tutorial. I just drew them in Photoshop on a Cintiq. I made multiple passes of each and then chose whichever one I felt best captured the spirit of the person while keeping to the general design laid out for the character line.