I don't know of a converter program.

You can copy/paste your Word document into the fax cover editor, but it will
be pasted as a graphic. That may be enough for you, but if you want to
create a cover page with fields for subject, sender, recipient etc. I think
you will need to do the conversion manually, copying each element of the
Word document at a time. e.g., to copy text you can create a "text box" in
the cover page editor, then copy/paste text from Word into it, and so on.

Peter Jamieson