Pointing Visual Studio 2008 to the source code of a third-party DLL for debugging

I have a VS 2008 C++ project which uses a third-party library (Open Scene Graph).

When i start debugging the project, each time a function from this external library is called, the debugger just jumps over it, because (obviously) the debugger has no .cpp files where to look up the code. It only jumps into header files which are linked to my project because those files exist and their location is known. So, i can only see what's going on in those small inline functions, but not in the bigger functions whose implementation is in .cpp files which i don't have.

I need is to somehow step thru the source code of these third-party dlls/libs the same way I do with my own code.

I downloaded the the whole source code of that library and compiled it on my machine. Now i have the dlls and libs, and the .pdb files, and the .cpp files, too. But how exactly do I tell Visual Studio the locations of the .cpp files of the third-party library, so that it knows, that when i want to step into a function coming from a .dll or a .lib it opens the corresponding .cpp file (even though it's not in my project and is located is a completely different folder)开发者_StackOverflow社区?

Is this at all possible?

I tried copying the .libs, the .dlls (debug versions), .pdbs both to the locations which my Project uses and "Additional Library Directories" and to the project's folder but this must be not enough.

Add the dir with the PDB files to Tools -> Options -> Debugging -> Symbols.