That would entail a little more creativity. Use a bigger piece of leather, of course, that is the length of the stem. Maybe make it a pointed so that it snuggles the tip of the starter and help hold it tighter. Getting the stitches inside the "tube" will be a bit harder. Lay out all the holes on both sides and punch the holes with the tube on the strap so that they all line up. You are going to need fairly long needles.
Start at the very bottom hole and put the outside of the tube onto the strap. Almost like you are going to sew it inside out. Then work your way up one side in the same manner, with the outside against the strap. It's going to get complicated. Fold the tube over and start at the bottom again. Insert your needle from the inside of the tube and just work your way up. It's gonna be a pain, but it will work.
Is that clear as mud?