add alias for localhost in /etc/hosts using Augeas

I am trying to use augtool to auto edit my /etc/hosts, as I wish to add an alias for localhost (so that I can test my webserver with a different host-name, localy). I have been looking every-ware to find good documentation. I with to find the node with ipaddr of 127.0.0.1 and add an alias to it. I would also like to find some good documentation to Augeas.