I suppose you don't really need to know C++ for Cinema 4D, you just need to have some experience with 3D modelling.
It's important for you to know the "Hello World" and how basic things works, so you can create more advanced applications. I learned the basics through some books I bought, but they teach you in a Game Programming vision, so it may not be useful to you.
I've never done anything through Cinema 4D or anything 3D modelling related so I can't tell you exactly what you want, sorry.