Using mingw-pkg in Windows to install to a staging directory

My first attempt to use mingw-pkg to install software to a staging 
directory  failed with my Windows-built gcc-5.3.0.

I now have a successful build of gcc 5.4.0, which like my 5.3.0 build,
was done manually , and I would like to try again, but I would like
to get some explicit instructions on how to use the mingw-pkg install 
action and what initial directory structure that I need to set up a
staging directory so that "mingw-pkg INSTALLDIR = ...  install" might work.

So far, I have found the the patch and configure actions for mingw-pkg
work with msys for a native gcc build but compile does not work.



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