Again, i don't know a thing about GLScene, but how it's done in other methods you need to know how math behind it works. Bone is usually a 4x4 matrix. To rotate bone you create a "rotation matrix" and multiply original bone with the rotation
(Original_bone_matrix * Rotation_matrix = bone_turned_around)

BUT after that you need to be sure that vertices assigned to bone will still follow with the bones. This is GLScene specific question and propably automatic.

If i remember right there is Geometry.pas unit in GLScene that propably contains all needed functions for you. However you need to find out yourself where the bones are in object data, or if there is functions already made to make it much easier.

http://www.cprogramming.com/tutorial...nMatrices.html
http://en.wikipedia.org/wiki/Rotation_matrix