I don't think there's any way normally within the settings of iTunes to do such a thing.
Although, a quick Google found me this guide: Guide on Copying Songs from iPod BACK to your computer.
Granted, I don't know if this works, but it's worth a try. If you have the ability to back your music up on DVDs/CDs, it'd be less of a hassle to do so.
Also, if you have something besides an iPhone or iPod Touch, you can try this.
[YOUTUBE]FtRFsX6FBVo[/YOUTUBE]
Hope this helps in some way.
Although, a quick Google found me this guide: Guide on Copying Songs from iPod BACK to your computer.
Granted, I don't know if this works, but it's worth a try. If you have the ability to back your music up on DVDs/CDs, it'd be less of a hassle to do so.
Also, if you have something besides an iPhone or iPod Touch, you can try this.
[YOUTUBE]FtRFsX6FBVo[/YOUTUBE]
Hope this helps in some way.