The Mac VirtualGL Client is an X11 application that must be run with an X
server.  To do this,

-- Install the Mac X11 Application (available on the OS X 10.7 and earlier
installation discs) or XQuartz (http://xquartz.macosforge.org).

-- Start the X11 application (in Applications->Utilities)

-- Start a new xterm (Command-N) if one isn't started already

-- In the xterm window, you can now use the VirtualGL client applications
as described in the VirtualGL documentation.
