Hey, I've been working on a script that is kind of a fork from your HorizontalScrollSnap script attempting to overcome some of the issues that I've been having with the HSS script.
I have posted it on the Unity forums but was hoping you could also check it out and give some feedback. I would really appreciate it. And of course if you like it feel free to include it in this library. The only thing that would need to change is the tweening stuff so its not relying on iTween.