All you need to do is extract the files Works with 2.8.1 version of CK2 and the WTWSMS version compatible with that (sorry can't remeber it
Make sure you are using Anime Portraits 2.8.X by Art
In case you haven't got it already
Extract the files into \Documents\Paradox Interactive\Crusader Kings II\mod\
and boom you are done.
Probably won't work with other portrait replacers.
This works with the installer version of WTWSMS not sure about the steam download yet. Been unable to download it as the Workshop for CK2 doesn't work half the time especially when it comes to big mods.
If you can tell me if it works with the Steam download