This week we got to see the first public Project Viewer for the Materials System. I’ve added a link in the left column. It is a dynamic link so it should always point to the latest version.
The current version is: Second Life 3.5.1 (273518) Project Materials.

Download size is just under 30mb.
It installs to its own directory and has its own settings files. It does however, share chat logs and the cache. I suggest you change the cache to use a location other than the main viewer’s cache. You can go into Preferences->Advanced->Cache Location and change it. Then restart the viewer.