First shut down iTunes all of the iPod related services(“Apple Mobile Device” and “iPod Service”). Connect your iPod and it should appear as another USB drive. Copy the files you want (you may have to show hidden files and folders) to the “Automatically Add to iTunes” folder. Restart the iPod related services and iTunes.
I can’t gaurantee that this method will work for all models but it does work on Every model I tried it on. Also the filenames on the iPod will not make sence but if the files are tagged properly you can read the tags.