It's possible to backup your DreamHost account using rsync. Please bear in mind the DreamHost already has a fairly good backup policy (https://panel.dreamhost.com/kbase/index.cgi?area=2585&keyword=backup) but you may want to mirror your website locally for whatever purposes. This is not a particularly user friendly approach: you will require a certain amount of technical knowledge.

In order to use rsync, you must have shell access to your DreamHost account. You must also have OpenSSH and rsync installed on your local machine. These software packages are included with most Linux distributions, and are available to Windows users via cygwin