This program is a wrapper for msvc's cl.exe and intended to be used with Windows 10's "Bash on Ubuntu on Windows" shell. It is invoked with gcc options (only a limited number) and turns them into msvc options to call cl.exe. The msvc options may not exactly do the same as their gcc counterparts.
The default search paths are set at compile time through header files.
See the files in the config directory for examples.
Instead of installing the full Visual Studio IDE you can also get the standalone command line build tools at Visual Studio's homepage: http://landinghub.visualstudio.com/visual-cpp-build-tools