Log in and out of iTunes account on separate computer Is it possible to use someone else's computer, log out of their iTunes account, log into your own account and access your own library on their computer?
Yes, it's possible, but it takes quite a long time. The simplest way would be to enable iTunes Match on your own computer, and then sign in to the other computer. Another way would be to backup the com.apple.iTunes.plist file in your ~/Library/Preferences directory to an external hard disk, along with the ~/Music/iTunes folder. Then, on the other person's computer, move their com.apple.iTunes.plist file to a safe place (desktop, etc) and copy your com.apple.iTunes.plist file to their Preferences folder (see path above). Then, repeat the process for the iTunes folder in their Music folder.

It's complicated, but it works well for me.

P.S. Don't forget to replace the original person's files.