Shorty, you might find a rig like this a little bit more portable, but otherwise its almost the same setup.
Also, I think it was mischi looking for a sub for vice grips...
Here goes.
With a table puller (or barstool as you will see in my pix post) and clam cleat (or side cleat like Shorty uses), you do not require any slack in the vertical. As you pull down on the one with the cleat, pull the next one AHEAD of it with your free hand so as to take up the slack as you create it. There is almost no slip back at all, at least comparable to using vice grips and there is NO WEAR on the rope save the minor damage you do with the cleat.
SUPER BONUS, once you get the hang of pulling two ropes at the same time, one with the cleat and one with your hand, you can tune a drum very quickly and because it is so easy (you really do have to be careful) you can pull all the verticals very consistently which I think to be of more importance than whether or not you can tune up the drum without knots (I can, I choose knot to).

- stool two.jpeg (67.41 KiB) Viewed 138 times

- stool one.jpeg (29.45 KiB) Viewed 138 times
I have skinned and tuned over 200 djembes on this contraption. I put it together for about 50$