First Mac

• 1). Select "Finder" to open a new window. Choose "Go > Go to Folder."
  
  
• 2). Type "~/Music/iTunes" and hit "Go."
  
  
• 3). Click on the "iTunes Music Library.xml." Wait for it to open in TexEdit.
  
  
• 4). Copy and paste the Library Persistent ID key (a string of 16 numbers and letters) into a blank document or write it down.
  
  

Second Mac

• 1). Select "Finder" to open a new window. Choose "Go > Go to Folder."
  
  
• 2). Type "~/Music/iTunes" and hit "Go."
  
  
• 3). Highlight both the "iTunes Music Library.xml" and "iTunes Library." Hold down "Command" and "C" simultaneously to copy both files.
  
  
• 4). Double-click on "iTunes Music Library.xml" to open it. Copy the Library Persistent ID key into a blank document or write it down somewhere. Erase those numbers in the document and replace it with the Library Persistent ID from the first Mac. Save the file.
  
  

Using Hexidecimal Editor

• 1). Download a hexidecimal program onto your Mac (see Resources). This program allows you to edit any file size in a hexidecimal format. Install it on the computer and open the program.
  
  
• 2). Click on "iTunes Library" to open it. Go to "Find" and paste the Library Persistent ID you copied over in the first section. Chose "Hex" and hit "Enter."
  
  
• 3). Find the old Library Persistent ID in the spreadsheet and replace it with the one from your first Mac. Save the file.
  
  
• 4). Connect your iPhone to the Mac and launch iTunes.