How to point SQL Server Python to a specific Python install?
You cannot point SQL Server to a different Python installation; per the docs you linked:


  SQL Server does not modify the Python executables, but you must use the version of Python installed by Setup because that version is the one that the proprietary packages are built and tested on. For a list of packages supported by the Anaconda distribution, see the Continuum analytics site: Anaconda package list.


The Python 3.5 runtime and interpreter are available from this site.