The Dell Recovery media creation tool supports two different usage modes, "End User Mode" and "Builder Mode". In End User mode, the tool will simply create an image from an existing recovery partition with no customizations. In builder mode, the tool allows modifying the source of the base image, the source of the framework, as well as injection of additional content.
When a customer receives a Dell machine that has been factory shipped with Linux, there will be an icon available in GNOME shell to launch this tool. They will be prompted for what type of media they would like to create.
If a DVD burner or USB port is found on the machine, customers will be offered to create media at the end of the out of box experience.
In builder mode, the user will be offered a variety of options that allow them to create ISOs based upon different snapshots of release upon standard Ubuntu media.
The latest information on how to use builder mode will be documented within the integrated help dialog.
Due to the nature of including a recovery partition, the installation flow varies from the standard Ubuntu installation. It is further documented here.
Dell recovery is built with an integrated Ubiquity plugin. It is branched with each Ubuntu LTS release and has code that will tightly integrate with Ubiquity for factory installation. Documentation for all of the features in Ubiquity mode and how to create packages to support it are stored outside of the dell-recovery tree.
Information about how to modify a factory image are available here.