I just wrote and committed folder-add.tcl which allows you to add a folder from the filesystem, actually working recursively (at least it should, no time to test yet). This is on 5-2, as OpenACS resides on 5.2. I just used folder-zip-upload.tcl and took out the code of extracting the zip file. Rest worked like a charm.
So, if someone uploads the old content to the filesystem and updates the file storage application, we should be fine.