If it's only a question of executing python, why not directly execute python from C++ using the python library?
#include "c4d.h"
#include "lib_py.h"
PythonLibrary pylib;
pylib.Execute("import c4d\nprint 'From Python:', c4d.GetC4DVersion()"_s);
Note that in R20 the python.framework was released, and should be used for the future.
The old python library (since R15) is still there and still works, but take care that in a future release it may disappear since everything that was possible and even more is now possible with the python.framework.
For more information see Python Page.
Cheers,
Maxime.