Suggestion:

• Create a folder (Admin File management) where the Event Editor has read/write rights
• Use the Standard FCK edit toolbars in the Event editor window
• Use the Insert/Edit Link button in the toollbar when you want a  file on that position in the text
• Use the Browse Server button in the pop-up window
• Use the File option for the link
• Position to the folder that has been created
• And your Editor should be able to upload a new file

The Event text now contains the (download) link to the newly uploaded file.

Is this a workable solution?

Please note that the file is not send as an attachment in any Event notification.