What I can recommend if you are okay with buying a book is this guide.
The documentation(can also be found in the installation of PyWin32) and Active State's doc(with their list of objects and modules) should do the rest.
Python Programming On Win32 from O'Reilly is a great, if dated, book on the subject. I've read it and is very good.
Its not documentation, per se, but its really useful for a good introduction to COM programming with Python, among other advanced stuff.