A script to register Python under HKEY_CURRENT_USER in addition to HKEY_LOCAL_MACHINE

win_register_python.py

#
# script to register Python 2.0 or later for use with win32all
# and other extensions that require Python registry settings
#
# written by Joakim Loew for Secret Labs AB / PythonWare
#
# source:
# http://www.pythonware.com/products/works/articles/regpy20.htm
#
# modified by Valentine Gogichashvili as described in http://www.mail-archive.com/distutils-sig@python.org/msg10512.html
# modified for Python 3 support by Erik Bray <erik.m.bray@gmail.com>

from __future__ import print_function


import sys

try:
    from winreg import *
except ImportError:
    from _winreg import *

# tweak as necessary
version = sys.version[:3]
installpath = sys.prefix

regpath = "SOFTWARE\\Python\\Pythoncore\\{0}\\".format(version)
installkey = "InstallPath"
pythonkey = "PythonPath"
pythonpath = "{0};{1}\\Lib\\;{2}\\DLLs\\".format(
    installpath, installpath, installpath)


def RegisterPy():
    try:
        reg = OpenKey(HKEY_CURRENT_USER, regpath)
    except EnvironmentError as e:
        try:
            reg = CreateKey(HKEY_CURRENT_USER, regpath)
            SetValue(reg, installkey, REG_SZ, installpath)
            SetValue(reg, pythonkey, REG_SZ, pythonpath)
            CloseKey(reg)
        except:
            print("*** Unable to register!")
            return
        print("--- Python", version, "is now registered!")
        return
    if (QueryValue(reg, installkey) == installpath and
        QueryValue(reg, pythonkey) == pythonpath):
        CloseKey(reg)
        print("=== Python", version, "is already registered!")
        return
    CloseKey(reg)
    print("*** Unable to register!")
    print("*** You probably have another Python installation!")

if __name__ == "__main__":
    RegisterPy()

FWIW, I had to prepend 'HKLM' to regpath:

regpath = "HKLM\\SOFTWARE\\Python\\Pythoncore\\{0}\\".format(version)

for it to run... and still, I had to to in and edit registry by hand (although, this was the correct key...)