So you have a base skin plus a normal map. Well, I'm not really good at 3D programming and this is pretty complex. These links may help you get started, otherwise I'll have to defer to others here more into 3D stuff. These are OpenGL tutorials too, so they should work with GLScene, etc.

http://www.delphi3d.net/articles/vie...umpmapping.htm
http://www.sulaco.co.za/opengl.htm