How to Change OS X Leopard Login Screen
If you are feeling bored with the default login screen of Mac OS X follow our guide on how to change login screen of Mac OS X. The default login screen is saved in the System >> Library >>CoreServices. First of all choose your desired login screen you wants to apply then rename it to DefaultDesktop. After you rename the file the image should be named as DefaultDesktop.jpg Now follow the steps given below. You can reverse this anytime by deleting the login screen you applied and perform the command in step two by replacing DefaultDesktop.jpg and DefaultDesktop.orig.jpg with each other.
1 : Now open terminal and type the following command without quotes
2 : Now rename the default login screen with the following command
“sudo mv DefaultDesktop.jpg DefaultDesktop.orig.jpg”
Now enter your password and press enter.
3 : Now open the finder copy the jpg you downloaded and renamed to Default Desktop earlier to System >> Library >>CoreServices.
4 : This is the final step of the procedure just right click on the image and and unlock the lock icon at the extreme right bottom corner. Now expand the Sharing & Permission tab and change all the three permissions to Read & Write.
5 : Now Reboot or logout and enjoy the new login screen. Check my login screen in action below.