Basis for a _Cursor style addon that works in patch 7.2

Cursor.lua

local CursorFrame = CreateFrame("Frame", "CursorFrame", UIParent)
CursorFrame:SetFrameStrata("TOOLTIP")
CursorFrame:Show()

CursorFrame.Presets = {
  ["Electric, blue long"] = {
    ["Path"] = "spells\\lightningboltivus_missile.mdx",
    ["MagicNumber"] = 148.1,
    ["Facing"] = 0
  }
}

_CursorOptions = {
  ["Cursor"] = CursorFrame.Presets["Electric, blue long"],
  ["Scale"] = 0.03
}

function CursorFrame.LoadModel(options)
  local model = CreateFrame("PlayerModel", "CursorModelFrame", CursorFrame)
  model:SetAllPoints(nil)
  model:Hide()
  model:SetModel(options["Cursor"]["Path"])
  model:SetFacing(options["Cursor"]["Facing"])
  model:SetScale(options["Scale"])
  model:SetFrameStrata("TOOLTIP")
  model.MagicNumber = options["Cursor"]["MagicNumber"]
  return model
end

do
  local model = CursorFrame.LoadModel(_CursorOptions)
  model:Show()

  -- Maximum values GetCursorPosition() can return
  local MAX_X = 1365
  local MAX_Y = 768

  local offsetX = MAX_X / 2
  local offsetY = MAX_Y / 2
  local scale = model.MagicNumber * model:GetScale()

  local previousX, previousY

  CursorFrame:SetScript("OnUpdate", function(self, elapsed)
    local cursorX, cursorY = GetCursorPosition()

    -- Do nothing if the cursor hasn't moved
    if cursorX == previousX and cursorY == previousY then
      return
    end
    previousX, previousY = cursorX, cursorY

    -- Normalise the mouse coordinates between -1 and 1
    local normalX = (cursorX - offsetX) / offsetX
    local normalY = (cursorY - offsetY) / offsetY

    -- Maximum distance the model should appear from the center of the screen
    local modelRangeX = MAX_X / scale
    local modelRangeY = MAX_Y / scale

    local posX = normalX * modelRangeX
    local posY = normalY * modelRangeY

    model:SetPosition(0, posX, posY)
  end)
end

please write some installation instructions