There are many options for this, depending on what you want to do.
You can scan a real stent and warp it to the vessel’s geometry using the transform computed by Curved Planar Reformat module.
You can paint the stent pattern in Gimp or Inkscape, save it as a png, then apply it as a pattern to the model. You can warp this to the exact geometry using Cardiac Device Simulator module in SlicerHeart extension as we did it for a non-textured model here.
For more realistic warping, you can design a straight stent in a CAD software then use finite-element modeling to fit it into the vessel. It is not a very simple simulation (first you need to compress the stent, then enable vessel surface boundary condition and gradually decrease the compression force to let the stent open), but we have done a successful feasibility study of this with Slicer and FEBio Studio.