This mod emits many script warnings to the console but in my extensive playtesting works just fine - at least nothing has been visibly or noticeably broken.
Mlox had this to say about MCA:
Version 6.* and 7.* of Neoptolemus' "Morrowind Comes Alive" use the heads and hairstyles from "Westly's Master Head Pack", which you don't need to have activated but you need to ensure you have its meshes and textures installed. (Ref: MCA - Readme.txt)
MCA.esm MCA - TR Addon.esp