Edit Word Doc On Web Before Download

I have a web site which has a Word document for users to download. Before they download I would like to edit the document to insert the username (they have logged in to the web site so I know who they are), and a unique file ID number that I have generated, in the footer of the document.

I can already edit the document locally on my office PC from an Access database using Visual Basic for Applications but how do I set this up to happen automatically on my web server?

Any help/suggestions would be appreciated.