Avsitter is now free and open source. You can download the scripts at GitHub.com/avsitter
the documentation is there or on the sl wiki. Doing a quick search in google will get you there also.
code violet sells avsitter with all the demos available for you to read and look at but, it’s insanely priced at nearly 3k. Maybe 2500. Still a lot either way you look at it for examples that you can only use as a reference to look at.
I am responding to this pretty late- hopefully you already have it.