How to add reference to EnvDTE project?

Question

Hello, I have the project getting using DTE with C++:

pSolution->get_Projects(&pProjects);
CComPtr<EnvDTE::Project> pProject;
pProjects->get_Items(1, &pProject);

Then I need to add reference to this project. How to do that? As far as I know VsLangProj namespace is not accessible for C++ code. Thanks