Step 1: Download and install latest version of iTunes
Step 2: Download and install latest version of Multi-Plugin. Multi-Plugin adds skinning support to iTunes on Windows.
Step 3: Download an iTunes skin from our iTunes skins gallery, and extract its contents to your iTunes\skins folder.
Step 4: Launch iTunes then simply go to Preferences > Multi-Plugin and select your new skin.
For comments and questions please go to this thread on forums.