I ended up adapting a script (http://effbot.org/zone/python-register.htm) to register a Python installation in the registry. I can pick the Python to be the Python in the registry, run the Windows installer, then set the registry back:
# -*- encoding: utf-8 -*-
# script to register Python 2.0 or later for use with win32all
# and other extensions that require Python registry settings
# Adapted by Ned Batchelder from a script
# written by Joakim Löw for Secret Labs AB / PythonWare
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
reg = OpenKey(HKEY_LOCAL_MACHINE, regpath)
reg = CreateKey(HKEY_LOCAL_MACHINE, regpath)
except Exception, e:
print "*** Unable to register: %s" % e
SetValue(reg, installkey, REG_SZ, installpath)
SetValue(reg, pythonkey, REG_SZ, pythonpath)
print "--- Python %s at %s is now registered!" % (version, installpath)
if __name__ == "__main__":
Run this script with the Python you want to be registered, and it will be entered into the registry. Note that on Windows 7 and Vista, you’ll need Administrator privileges.