I had the same problem when I first started using the rubber tubing alignment system. The directions didn't say how to attach the anchor end of the tubing, but from looking at catalogs and bowhunting mags, it looked to me like everyone tied it directly to the down cable. I tried this, but the peep was always rotating to the left just a little because the cables are intentionally held off of centerline by the cable bar. Doh!
So I solved the problem by using one of those tie wrap stick-on plates(available from Radio Shack), that are used to tie up computer cables and have an ultra strong sticky tape on the back. I attaced it to the limb right above the riser pocket.
It looks a little strange, but it works like a charm!
As a side note... I change my surgical tubing every year since it's cheap enough, and I woudn't want to get "thwapped" in the eye should it ever break!