Prior to version 9 all documents, both embedded and linked, are stored as OLE package objects within the address book "Letters" file (MXZL.MAX). Access to the documents outside of the Maximizer user interface is *not* a trivial exercise.
That said, some Business Partners have built tools to manipulate documents. For example, see the reference to "Linked Document Mover" and "Document Extraction" on
cabc.co.uk/download/other_projects.htm
(Disclaimer: I don't work for CABC and I have not used either of the tools mentioned.)