In addition to creating custom switchlist styles, SwitchList also lets you customize the look of the homepage for the iPad web interface and the per-layout page in the web interface.
To replace the initial page you see on contacting the web server, you'll create your own version of the switchlist-home.html file, and to replace the layout page, replace switchlist-layout.html . Place your versions in ~/Library/Application Support/SwitchList. Currently, only these two files are customizable; you can't include separate CSS or images in the SwitchList directory.
Detail: SwitchList web interface / SwitchList on your iPad
Customization: Creating Custom SwitchList Styles