1) Check src\Makefile.vc to ensure that PYTHONDIR is pointing to your Python installation, either a 32-bit or a 64-bit (x64) installation of Python will do.
2) Open an MSVC Command prompt and run "nmake Makefile.vc CFG=release" or "nmake Makefile.vc CFG=debug" in src\ for a release or debug build.
3) Optionally, add src\ into your PATH and run the previous step in test\. Run the tests by running the built .exe's.
4) Assuming you want to install in %INSTALL_DIR%, copy gl.h, gl_generated.h, wgl.h, wgl_generated.h, egl.h and egl_generated.h from include\epoxy\ to %INSTALL_DIR%\include\epoxy\, copy src\epoxy.lib to %INSTALL_DIR%\lib\ and copy epoxy-vs12.dll and epoxy-vs12.pdb (if you've built a debug build) from src\ to %INSTALL_DIR%\bin\. Create directories as needed.
4) Assuming you want to install in %INSTALL_DIR%, copy common.h, gl.h, gl_generated.h, wgl.h, wgl_generated.h, egl.h and egl_generated.h from include\epoxy\ to %INSTALL_DIR%\include\epoxy\, copy src\epoxy.lib to %INSTALL_DIR%\lib\ and copy epoxy-vs12.dll and epoxy-vs12.pdb (if you've built a debug build) from src\ to %INSTALL_DIR%\bin\. Create directories as needed.
5) To clean the project, repeat steps 2 and 3, adding " clean" to the commands.