If you have any mainstream bass tackle stores near you, you can buy little tapered rubber sinker stops. The bass guys use them for keeping their sliding sinkers in place. They are about two inches long, taper from a very thin point to about 1/8 inch, and don't cost too much. After you loop your strike indicator in place in the normal way, slide one of these through the hole, pull it tight, then trim it. Leave it about 1/2 inch long, and when you need to move the indicator, just pull out the stopper, move the indicator, and then replace the stopper. You can do the same thing with a large enough rubber band, but then you have to either taper cut them or rig a loop to pull them through. Either way works quite well (Gene Hill, like many of us, has his own opinions about how to fish. His has no more or less validity than yours or mine.)