Think of the ICC as simply a curve (an S curve). Lightroom is the layout program (same as Print-Tool or Photoshop) so the workflow is really exactly the same
so, Lightroom/Print-Tool/Photoshop → ICC (or no in the case of Print-Tool) → QuadtoneRIP → Printer.
QTR does all the ink stuff still. Why are you assuming you have to use the Epson driver or something? Why are you confusing yourself here?
NO! Have I ever written in any of the thousands of pages of words on the subject that have come from my fingers that you can use the Epson driver for Piezography?