Adding or Modifying Devotion Nodes

Hello, I’m looking to start messing around with modding and I had a quick question. Could someone point me to a tutorial or give me some guidance for modifying the devotion tree? I’ve read that it isn’t impossible, just tedious, however I haven’t found any information on how to actually accomplish it. I’m only wanting to add a new independent node or set of nodes, not alter the appearance of the base tree (aside from the nodes being visible), thank you.