Very bottom of website gives you the way to do it…
http://www.stonehearth.de/weblog/blender/manual-english/manual-2-workflow#22
You basically need to set the origins of the parts of your character in the place you want to pivot around.
Voxel_Pirate’s tutorial on animation with origins
Then add helper bones. (Website I posted above has all of the information somewhere…)
Then export as skeleton.
This one of @voxel_pirate’s videos has the placement of the helper bones of a female settler. (toward the end)
(root, body position, main hand, off hand)(I think you need root and body position for anything…)
I figured out how to do this a few weeks ago, but I am sill missing a lot of parts to be able to implement it into the game.