Here is some example code for getting an idea how to access Plone content for the purpose of an migration export.
Possibly you can do the same using Transmogrifier...or you write a custom script using plone.api yourself (perform a catalog search for 'File', get hold of the related File object and use the Archetypes field API for getting hold of binary data and metadata (my script is doing the same).
Thanks, I'm trying this out. I'll let you know how I get on. I need to migrate all the content to SharePoint, so I will need to design some sort of script which parses this JSON representation of these files into SharePoint friendly format. Do you know of any scripts which can be used for this purpose?