I needed to be root in order to install crossover office shell script. Using sudo would not work. To sort this out I opened a console and:
sudo passwd
I entered the password I wanted for the root user and then entered the following which allowed me to log in as the root user:
su -
For installing some software e.g. Crossover office I needed to run the following at the command line:
xhost +
This gives all users (including root) access to the XServer.