How to install framework (from pkg file) in a non-standard location?
You can safely install Python under /Library/Frameworks and not worry about it interfering with the "system" Python, although with a few symlinks and/or $PATH changes you can make it the default if you want.

As an alternative, you can install MacPorts and set its install root to whatever you want (the default is /opt/local, I believe, although this is configurable during setup), although the Python framework will still be installed under a Library/Frameworks subdirectory. I prefer the MacPorts distribution over the python.org one because there are many additional modules you can install which are pre-configured to build correctly, which isn't always the case when you use pip or easy_install, depending on what you're trying to build. MacPorts also has a pretty decent versioning system, allowing multiple versions to coexist side-by-side, with simple tools to switch between them. As an added bonus, the MacPorts Tcl is not "broken," so everything should work out of the box. YMMV :)