TuneSwitch is a small application that allows you to manage multiple iTunes accounts .
Upon first launch, TuneSwitch will offer you the possibility to create a Keychain entry for your first account.
After that, enter your iTunes Store Account name (like firstname.lastname@example.org or whatever your AppleID might be).
Now enter your password and hit OK. This will create a keychain entry named “iTunes: ”
When your’e done or you already have iTunes accounts in your Keychain you’ll get a list. Either choose one or click “Create new Keychain entry” to create another entry.