Hello,
If you want to use Python Portable, you can download setup in this website : www.portablepython.com
When you installed this package, there are 3 executable Python on your PortbaleApps Menu.
You can change it with this howto : http://arawn.fr
It's ok for you ?
as well, but still in developement:
https://portableapps.com/node/12031