register.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
 
import sys
 
from _winreg import *
 
# tweak as necessary
version = sys.version[:3]
installpath = sys.prefix
 
regpath = "SOFTWARE\\Python\\Pythoncore\\%s\\" % (version)
installkey = "InstallPath"
pythonkey = "PythonPath"
pythonpath = "%s;%s\\Lib\\;%s\\DLLs\\" % (
    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()

Idêntico ao encontrado em
http://opensourcehacker.com/2011/02/22/changing-the-active-python-interpreter-on-windows/

Utilizado para registar a instalação de Python do OSGEO4W.
O script register.py está em %OSGEO4W_ROOT%\apps\Python27\Scripts.
Modifiquei o ficheiro %OSGEO4W_ROOT%\etc\ini\python.bat:

  SET PYTHONHOME=%OSGEO4W_ROOT%\apps\Python27
  SET PYTHONPATH=%OSGEO4W_ROOT%\apps\Python27\libs
  PATH %OSGEO4W_ROOT%\apps\Python27\Scripts;%PATH%
  python register.py 

(e o registry fica com duas entradas... incluindo a anterior do C:\Python27\ArcGIS10.1\ ... isto vai dar asneira)