Quando você executa vmbuilder <hypervisor> ubuntu --help
, gera uma página de ajuda na qual eu leio
--iso=PATH Use an iso image as the source for installation of file. Full path to the iso must be provided. If --mirror is also provided, it
will be used in the final sources.list of the vm. This requires suite and kernel parameter to match what is available on the iso,
obviously.
Eu não tentei isso, no entanto.