Gettin' some hate on for Python

So, I'm working on a Python project again. And, like usual, I'm finding a dearth of helpful tutorials for advanced hacking. The current problem? I have a module that I want to break up into a package in order to make it easier to mess with, but I want foo/__init__.py to export the same API as the old foo.py did— that is, not breaking old code by requiring extra namespace qualifiers.

I've managed to hack something together that mostly works, but I'm far from pleased. Client code can import the package like usual, and that seems to work. But the library's doctest tests don't work anymore because of an ImportError from python not being able to find submodules, despite having found them just fine for the client programs.

And for trying to debug this the internet is useless. All the searches I've come up with give a pasted copy of the official module tutorial, or are specific projects' FAQ pages giving such helpful explanations as telling me Python can't find the module (duh) or offering such helpful advice as adjusting the Python path so it can ((a) duh, (b) that's not the problem). I've yet to find any resources on how the module/package system actually works to know where things are going wrong.