I certainly don't mean to speak for Daniel, but are you sure he's using 3D people? He uses lots of 2D people in his work as far as I know. Search Daniel Tal on the Trimble 3D Warehouse and you'll find several 2D collections. If that's not what you're looking for, let us know.
The people that were used in his book, Google Sketchup for Site Design: A Guide to Modeling Site Plans, Terrain, & Architecture, appear to be 3D & whatever they are, I've got to have them. They're colorless and appear to be 3D. Very sharp.
In both of his books, Daniel mentions FormFonts as a good source of 3d and 2d material. Have you checked there?