There is no way to do it using iTunes because of copyright
protection. If you try to explore it using Windows Explorer you'll
find the files hidden and the song file names will be replaced by
numbers or letters in random order.
If you are using Windows, use Yamipod. Shut
off your iTunes without ejecting your iPod before
launching this application. No installation required.
If you are using Linux, there is Yamipod for Linux as well
If you are using Macintosh, you can either download Yamipod, or use
the more popular Senuti.