Is there a way to talk to OneNote through code?
OneNote 2007 has more options, but OneNote 2003 only supports the CSimpleImporterClass API for importing data programmatically into OneNote. CSimpleImporterClass will let you bring in images, ink, and HTML into OneNote using VB.
Reading OneNote 2003 files might be a little harder. I don't know of any resources to make it easy to ready OneNote 2003 files with Python or VBA.