It is possible adding a text string to the login window, for example you can add a welcome message, simply open a new terminal window and type the following command:
# sudo defaults write /Library/Preferences/com.apple.loginwindow LoginwindowText "Hi man”
you will be asked for a password, type your password and then log out from the finder. Now in the login window that will appear you will see the "Hi man" message. Naturally you can type the message you like.
If you have a long list of users you can have some difficult finding your own user, so you can think to remove some of them simply typing the following command:
# sudo defaults write /Library/Preferences/com.apple.loginwindow HiddenUsersList -array-add shortname1 shortname2
shortname1 and 2 will be removed from the login window
To make a hidden name appear again, type the command with no names in it.
Also you can change the Apple logo with you own one. The new logo must be stored in TIFF format and its dimensions must be 90×90.
In the Finder, choose Go to Folder from the Go menu or press Command-Shift-G. In the dialog box that appears, type the following line:
/System/Library/CoreServices/SecurityAgent.app/Contents/Resources/
A folder called Resources should appear. Change the name to the "applelogo.tif" file in "applelogo.tif.old" then move your image into this folder and rename the image in "applelogo.tif"
This should work…
Gg1