I need help with custom voicesets

I'm not sure if it counts as 'general modding' but can anyone help me out? I want to add custom voicesets into my game, as well as NPC ones (i.e. being able to select Mazzy or Neera's voices in character creation).

I'm on PC playing through Steam (though use cloud saves to swap between my mac).

Can anyone help out? Thanks so much.