Note: Do not plug in your iPod when CopyTrans is not running
I want iTunes to see my music on the external hard drive
First, follow these Apple instructions on how to Move your iTunes Media folder
Follow this guide to import your backup into iTunes.
Your songs will be added to your iTunes library without being physically copied to your C: drive.
I don’t want iTunes to see my music on the external hard drive
Please read the following FAQ article which explains how to create a simple backup to an external hard drive: How do I copy my iPod contents to a PC folder or an external hard drive (Backup to folder)?