Modify the PostEm tool to allow selecting from site resources (file picker helper) including reading from external URL resources rather than the single file upload. The File Picker Helper that exists for other tools in Sakai should be used since it already has both of these features.
The idea is that someone could create a spreadsheet in google docs, or attach the URL and post'em could use this rather than forcing the instructor to reupload
Ideally the PostEm tool would also periodically check for updates to the URL or Sakai Resource and update the data in PostEm when it changes. If this is not feasible, a button which allows the user to manually check and refresh the PostEm from that source should be provided.