The tube one is good.
Get a bit of high pressure tube from the hardware that is big enough that it won't go through the ring at the top of you powerstrap. cut about 5cm of it. Cut two slits in it about 1/3 of the way through and evenly spaced apart. Get the end of your line and go inside the bottom of the tube, out the top slit, in the bottom slit and out the top of the tube.
NB: Make sure the sleeve on the line is covering the section of line that goes through the pipe!
Hint: After going through the first slit, slide the stopper down to where you want it, then finish threading it.
HOPE THIS HELPS

L