Launch Cydia from your SpringBoard.
Tap to select Sections from the tabs across the bottom of the screen.
Select Utilities from the list of sections displayed.
Choose MultiTunes from the list of packages.
Press the Install button at the top right of the screen.
Press the Confirm button to begin installation.
Once the installation has completed successfully press the large Return to Cydia button.
Press the Home button to return to your SpringBoard and launch MultiTunes.
Press the + button at the top right of the screen.
Enter a name for a second library to be synced to your iOS device and press the Done button.
Select the library you just created from the list and then connect your device to iTunes and sync with the new library.
***Important: This app does NOT sync apps with multiple libraries, so be sure to only sync apps with your default library. Before downloading content from the iTunes app, make sure your default library is selected in this app. Otherwise, your content may not download properly.
You can now open at MultiTunes at any time to switch libraries.