1) Open up %appdata%, if you don't know how to do this, start>run, then type in %appdata%
2) Browse to .minecraft/bin
3) Open up minecraft.jar with WinRAR or 7zip.
4) save the image that I posted as kz.png and place it in the .jar under the folder called art
5) Delete the META-INF folder in the jar.
6) Run Minecraft, enjoy!
1)find mincraft.jar in ~/Library/Application\ Support/minecraft/bin/minecraft.jar
2) second click (or control click if you don't have a 2 button mouse) on the .jar file and chose open with Archive Utility
3) save the image that I posted as kz.png and place it in the unarchived folder under the folder called art
4) highlight all the content inside the folder second click it an hit Compress #### Items. you will end up with a file called Archive.zip
5) rename the zip as minecraft.jar when promoted chose "use .jar" (vs .zip)
6)move the the file to ~/Library/Application\ Support/minecraft/bin/ and delete the unarchived folder.
7) run Minecraft
Edit: the file I posted is already a .png file but it was renamed 37504109.png when I uploaded it to imageshack