I'd love to have include siege weaponry in a mod, it's just that I'm completely inexperienced with graphics... maybe Illwinter will chime in on whether or not the gfx are in there already so Wish_4_blood_slaves doesn't have to start
There's already some sort of machine in the UlmPunk mod, I don't remember what it does, though. Giving a unit a "spell" as a special ability is possible in mods, isn't it? Some sort of machine that casts Flying Shards or Blade Wind would be sweet...