There's a plentyful amount of mods and customization that you download and install for FeralHeart, but also make yourself if you have some extra time and patience on your paws.
In this case the changes to the log in page and menus are usually a skin/gui mod that changes the looks on the menus. Various people make these sort of mods in the community and many of them can be found here on the forum. But there's also other things like maps, sounds mods, texture mods for the characters, markings, items etc.
In most mods no matter what type it is, the a bit more experienced modders usually include instructions of how a user installs their mod to the game. If you are looking for these mods though they are in this section linked below.
http://www.feral-heart.com/index.php?option=com_jfusion&Itemid=2&jfile=index.php&board=34.0Just look in the section that includes the stuff you are looking for.
