There is a feature in Gnome which allow me to change the theme. I downloaded an Apple OS X theme, install the icons and the Splash Screen from GNOME-Look.Org. I modified some of the default icons from the theme. The result is a clean and nice desktop interface and login splash screen.In case you wonder how I capture the login screen, here is the trick, install Xnest (Nested Xserver). Here are the steps:
sudo apt-get install xnest
Then do the screen capture.