is there a way to import new Matcaps into Blender?
i dont think so, not without re-compiling, but they are crazy easy to setup.
in the blender internal, or game, add your mat cap as a texture and set the coordinates to “Normal”.
or, you can setup the nodes by plugging the geometry normal into texture vector, then the texture color to an output. these nodes can sit right next to your cycles nodes, so you switch to internal engine to get your matcap.
right now I do have a material setup to show my Matcap and it works great. I just don’t understand why don’t they add this as a feature, just let us use any image.