It is possible to change the login image and favicon on the authentication templates. This is done per authenticator in the configuration.
For images referenced from css files, please see the 'Style sheets' document.
How to use
Log in to the Configuration manager and open the ADVANCED tab.
Locate the authenticator and add the icon key and/or the favicon key as seen below.
Note: The favicon must NOT be called favicon.ico . Rename it to something different.