The skin support is provided by a custom modification to SkinLF, www.l2fprod.com, check my web site for more details. You can write your own skin if you wish, more info on the SkinLF site. You may notice some artifacts left over from changing skins, it is suggested to restart the server once you have chosen a skin to remove those artifacts. The skin included with the server are the one available on the SkinLF web site at the time of distribution if you would like to add your own skin simply at the zip file in the “lookandfeel” folder.