You can find the original post for Maximo 7.1 here but these are updated for Maximo 7.5 with the new login page design and the banner images on top.
Download these images for free below and to install these images, you can follow how I changed the BIRT report logo, or you just simply extract the ZIP file and copy the contents of the server type (prod, test, dev) folder into your MAXIMO installation directory, such as this:
Copy the files into the login and skins directory. I only made this for the ‘tivoli09’ skin, but you can copy the same images to your ‘mobile’ skin if you are using the free mobile skin for the iPad. Rebuild, deploy and enjoy!