If you want to install Multisystem dowload this sources http://liveusb.info/multisystem/multisystem.tar.bz2
Extract at /tmp/multisystem/multisystem
From the file /tmp/multisystem/multisystem/dependances.txt you must unmark with a # before them #kvm #genisoimage # fatresize and # xxd.
The other missing dependences listed when you execute the install.sh can be installed with emerge or Sulfur.
You must use the program loged as root.
As nobody is working it to make a Sabayon and or gentoo package any other trick is welcome
MDOERATOR EDIT: fixed Subject ("Multusystem" to "Multisystem")