Step 1: Finding in Finder
The first place you need to go is your machine’s Library folder. This is hidden in Mountain Lion, so you won’t see it in your normal user folder.
Step 2: Go, go, go!
Instead, use the Go menu. It won’t appear here by default either, but hold down the Alt key and the option will be revealed for you to click.
Step 3: Find the key
In the new Finder window scroll down until you find a folder called Keychains. Folders are ordered alphabetically. Be careful not to delete anything!
Step 4: Sharing keys
In the Keychains folder you will find a file called ‘login.keychain’. Choose Share and you’ll have a few options for sending it to your second Mac.
Step 5: AirDrop
You can use a USB memory drive to transfer the file if you wish, or simply use the AirDrop sharing sheet to quickly send it to another Mac wirelessly.
Step 6: Receiving
On your other Mac you’ll need to accept. The file will automatically be added to your Downloads folder – remember this as you’ll need to find it again shortly.
Step 7: Quick access
Next you need to add the Keychain to your Mac’s own. Open Spotlight and find Keychain Access – this is the app that will allow you to add the chain.