http://frostsoft.blogspot.com/2012/01/vertex-normal-tool-plugin_80.html

VNT is a plug-in for C4D which adds a tool for creating and manipulating vertex normals on polygon objects in C4d.

VERTEX NORMALS
Virtually all other high-end 3d applications (3ds Max, Maya, ...) support vertex normal editing and while c4d supports importing and rendering vertex normals it lacks any interface or tool for creating or editing them. VNT aims to address that problem by giving the artist full control over vertex normals.

• Complete tool kit which adds the ability to really work with vertex normals on par with other high-end 3d software.
• Easily add new vertex normal tags to objects while preserving any phong angles and edge breaks.
• Easily update and manipulate vertex normals with the ability to perform all common tasks like flipping, averaging, normalizing, setting hard or soft edges by selection or angle, etc...
• Built in functions for easily dealing with common vertex normals tricks.
• Steal or target another meshes normals.

So if you need to edit an object normals for any reason like:
Removing or tweaking any shading artifacts,
Remove nasty shading seams between seperate objects,
Improve shading across certain edges,
Bend Normal for special purpose like alpha plane hair, trees , grass, clouds etc..
VNT can help you achieve the desired results and is an incrediably usefull adition to any artists toolbox.