There are a couple of ways to host files on MWG. You could use the Template Editor (which is used to modify error templates). On the lower left you can see the "filesystem" area which allows to upload files using the "Add" button. As an alternative you can upload the file via SCP (or similar) into the /opt/mwg/files folder. The files become available as a link similar to http://<my MWG IP>:4711/files/myscript.js.