stuff/ __init__.py mylib.py Foo/ __init__.py main.py foo/ __init__.py script.py
s
though as long "stuff" is not in your python PATH you got no choice than adding the path.
If you know the level of your script.py from stuff you can do for example:
import sys import os sys.path.append(os.path.join(os.path.dirname(__file__), '..', '..'))