The sample I've described in my blog post can be used to create an XPage that can handle files that are (HTTP) POSTed to it.
To post a file to such an XPage you'd need to create (for instance) a HTML page, containing a file upload, with the form method set to POST and the action to the location of the XPage.
It's probably possible to change the code so it can handle a file upload contained on it, but I haven't tested that. The could would probably have to be moved to the querySaveDocument event.
Mark