Building a Debian based 64bit live system is as simple as running:
# grml-live -s sid -a amd64 -c GRMLBASE,GRML_FULL,AMD64
You can fully customize the build process, including adding additional software and your very own configuration files.
Further information is available from http://grml.org/grml-live/
In case you want to run grml-live directly from the checkout (after
making sure all dependencies are installed), you should set
GRML_FAI_CONFIG so that it does not use the config files of an
# export GRML_FAI_CONFIG=$(pwd)/etc/grml/fai # ./grml-live -s sid -a amd64 -c GRMLBASE,GRML_FULL,AMD64