The details for using Microsoft Visual Studio to create a C++ DLL than can be accessed from a Python script in Rhino has been documented in my post:
The Python and C++ code included in this document could be modified to deal with updating the vertices in a mesh if that is your objective.
Let me know if you have any questions. It took me some time to create my first working C++ DLL that I could call from Python but the effort was very worthwhile. Hopefully my document will shorten the time it takes to get your first C++ DLL working.
Regards,
Terry.