SItoA is no longer maintained by Autodesk. The official SItoA plugin source code can be found here.
for Arnold 5
This manual introduces SItoA, a plug-in for Autodesk Softimage which allows you to use the Arnold renderer directly in Softimage. Before beginning, you should read the sections on installation and licensing. Also, don't forget to look at the Tutorials section. We are adding new tutorials all the time.
Arnold Answers is a reputation-based forum where Arnold users of all kinds can ask their colleagues and peers questions related to Arnold.
Use the / key to perform a quick search.