First, download TightVNC - Go to http://www.tightvnc.com/download.html and download the Windows Viewer executable. The file at the time of this writing was tightvnc-1.3.9_x86_viewer.zip. Unzip the file, and copy the executable to your machine.

Second, set the 'live test settings' so it knows you want to use the desktop vnc option. This is access from the top of the live testing console - look for the 'live test settings' link.

When you start a CrossBrowserTesting configuration, you will not have long to log in, so have TightVNC launched before selecting a configuration. When the configuration becomes available, you will be presented with your connection information. This consists of 2 parts: a vnc host address and a password. Enter the VNC Host information in the VNC Server field and press connect. You will be asked the password - copy and paste it from the connection information given. You should now be connected. You can still use the CrossBrowserTesting console to take snapshots, end your session, and view information about the time remaining on your current credit.