Many of us like seeing what is new or need to get a bug fix that is in the works. Before the new viewer pipeline was implemented we just downloaded and installed beta versions of the viewer. With the new pipeline that is still possible, but it has gotten rather complex. It is easier to just install an RC viewer over the top of our main install of the SL Viewer and run a single SL Viewer.
I’m trying that for now and watching how things work. In general, pretty well. There are some Windows oddities I am still sorting out.
You can download a copy of the current Maintenance Viewer 3.6.7-281236 RC from the Beta/RC page. Before you install it, open your SL Viewer and check that you have Auto-Update and ‘willing to install RC’ options enabled. Then just install it as you could the main release SL Viewer. Some versions do wipe out your settings when installed manually.