Import them into his computer, then copy them from his iTunes Music folder to your computer via Home Sharing - http://support.apple.com/kb/HT3819 - (probably the easiest), file sharing, or an external storage device such as a USB flash drive or external hard drive. If you use any method other than Home Sharing, just drag the tracks into the iTunes window on your computer.
You posted in the iTunes for Windows forum, by the way. Just FYI for future questions.
Message was edited by: varjak paw