Get iphonebrowser for windows to browse your iphone,
taking care as all folders and files are case sensative
naviagte to /Library/Themes
create a new folder SEAT Logo
create a new folder Bundles under it
create a new folder com.apple.TelephonyUI under it
the file for the logo is bottombarknobgray@2x.png
In Winterboard you will have the new selection SEAT Logo