I don't pretend to know how. However I can suggest just meshing a model of a person then using built in animation tools in 3ds Max (if it has any) or using a 3rd party animator. I know I've seen some npcs in the catalog. Sorry I can't be of more help than that. I'm no where near that advanced in meshing, then again, I use Sketchup which is limited.
I don't know if looking at a product will help but here's one:
