Here's my edited version of Be A Zombie. I cleaned up the code a bit to my standards.
I removed the attributes as well as the dependency on TF2 Attributes as it seems the actual voodoo items themselves don't actually make the voice deeper.
And the 'Battle Cry' voicelines also automatically use the zombie voicelines when the voodoo item is equipped already.
However, it seems that the voodoo skin does not transfer over to the ragdolls.
EDIT: I might be a bit of an idiot, the ragdoll might need the 'zombie' attribute in order to properly transfer the skin over.