Because we create a chroot to build a liveCD, any Linux distro from Gentoo to Debian can work on Cherimoya. All you need to do is to install the pacman package manager to your host system.
Gentoo has a pacman package ready to go. Just unmask and emerge it:
# echo sys-apps/pacman >> /etc/portage/package.keywords # emerge -va sys-apps/pacman
Because Gentoo does not have libfetch, you will need to uncomment one of the two XferCommand lines in /etc/pacman.conf. I recommend using the wget line:
XferCommand = /usr/bin/wget --passive-ftp -c -O %o %u
For other distros, such as Debian or Fedora, they either do not have a Pacman package, or it is too old. Not to worry though, just download this script, run it, and pacman will be installed.