How To Change Leopards Dock

Go to Macintosh HD > /System/Library/Core Services/

Right-Click on "Dock" and select "Show Package Contents"

Go to /Contents/Resources/

Backup the files you are about to replace (Incase you did not listen, here they are)

Move those same original files to the trash

Move the files you downloaded to that folder

Open Terminal and type "killall Dock" (without the quotes)

View your nice new dock.