Hi there, very late yet I have a question- HOW DO I IMPLEMENT IT 
Viewing post in Dark Elegance Ren'py GUI template comments
Hi, if you want to add it to an existing project (make a safety copy of your game first) simply copy the screens.rpy, animations.rpy and gui.rpy and the gui folder to your game and it should work. If it complains that something is missing just open the template, locate where it is and copy over that file too.
You can do the reverse as well and have the template project and copy in your script and customize the options.rpy etc.