This situation was really bugging me, so I decided to let you know how to do. If you have your iTunes both auto-sync and auto-dismount enabled, you will see that you cannot access your ipod, since it automaticly dismounts after syncing from your library. Maybe there are easier ways, but after trying several methods, here is how I handled it:
1) Uninstall iTunes (to avoid auto dismount)
2) Connect your iPod
3) Go to the hidden folder called "iPod Control"
4) Delete everything in that folder (That will force iTunes to stay connected and restore the iPod)
5) Disconnect your iPod
6) Install iTunes
7) Connect your iPod
Now iTunes will say that your iPod is in recovery mode and needs to be restored.
8) Click OK and wait for iTunes to restore your iPod
9) After it finishes, DO NOT select "automaticly sync my music"
10) Now you can add your music manually, and disconnect your iPod whenever you like.
Hope it was helpful!
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