Yup, super easy. It should look like this on your local drive (assuming you're playing single player):
X:\Steam\steamapps\common\7 Days To Die\Mods\Snufkin_CustomZombies\Config
* archetypes.xml
* buffs.xml
* entityclasses.xml
* entitygroups.xml
* items.xml
* loot.xml
* physicsbodies.xml
* quests.xml
* sounds.xml
* spawning.xml
If you're running a server, create a "Mods" folder under the main 7 Days to Die folder. Then drop the Snufkin_CustomZombies folder into the Mods folder. Make sure you keep the folder hierarchy so that the Config folder and its contents remain underneath the Snufkin_CustomZombies folder. It sounds confusing but it really isn't - promise!
My group of friends and I really enjoy these custom zombies -- ESPECIALLY since they're server side only (no client-side download needed).