First Off: Install the Script Extender and Enable its Console
Secondly: Install DAF: Dynamic Appearance Framework

Commands:

List available Fangs visuals - The strings in the 'Option Key' column can be used in the other commands :
Mods.KvFangs.Fangs.List()

List available Horns visuals - The strings in the 'Option Key' column can be used in the other commands :
Mods.KvFangs.Horns.List()

Apply fangs with key XXXXX to currently selected character:
Mods.KvFangs.Fangs.Apply("XXXXX")

Apply horns with key YYYYY to currently selected character:
Mods.KvFangs.Horns.Apply("YYYYY")



Command Examples - Applying Visuals:

Apply 'Cazador' fangs to currently selected character:
Mods.KvFangs.Fangs.Apply("Cazador")
Apply 'Astarion' fangs to currently selected character:
Mods.KvFangs.Fangs.Apply("Astarion")
Apply 'Karlach' fangs to currently selected character:
Mods.KvFangs.Fangs.Apply("Tiefling_F_Karlach")
Apply 'Rhol' horns to currently selected character:
Mods.KvFangs.Horns.Apply("Rhol")
Apply 'Karlach' horns to currently selected character:
Mods.KvFangs.Horns.Apply("Karlach")



Command Examples - Removing Visuals:
Removing visuals works the very same as applying, just in reverse.

Remove 'Cazador' fangs from currently selected character:
Mods.KvFangs.Fangs.Remove("Cazador")