I think compiling python itself with it would be quite difficult - I
have never attempted it. My 'scenario' is building extensions against
the official python for amd64 on windows.

The quickest way to test the patch would be as follows:
 - take a native toolchain (by native, I mean runs on and target 64 bits
windows subsystem - I have not tested cross compilation, or even using
32 bits toolchain on WoW). The one from equations.com is recent and runs
well:

http://www.equation.com/servlet/equation.cmd?call=fortran

 - builds a hello-world like python extension from the command line:

http://projects.scipy.org/numpy/wiki/MicrosoftToolchainSupport (I am
sorry, the wiki page is bit messy, I will clean it up).

Since we use our own distutils extensions in numpy, I don't know how
much is needed for support at the stdlib distutils level. If that's
something which sounds interesting to python itself, I am willing to add
support in python proper for mingw-w64.