alias tmerge=PORTAGE_CONFIGROOT=CONF_ROOT ROOT=/root/target/image emerge -K (don't actually alias, just set env vars and use EMERGE_DEFAULT_OPTS=-K in make.conf)


generate a fake CONF_ROOT with /etc/make.profile (linked based on target arch) and /etc/make.conf (generated)
	make.conf:
	PKGDIR=...
	CFLAGS=?
	CXXFLAGS=?
	CHOST=...
	MAKEOPTS=?
	EMERGE_LOG_DIR=... (same as PORT_LOGDIR)
	PORT_LOGDIR=... (create me)
	PORT_TMPDIR=... (create me)
	FEATURES=ccache?
tmerge -p system (check that it doesn't mention unavailable packages) # Possibly merge with 
tmerge system
ln -s /usr/portage/profiles/x /etc/make.profile
tar -zxvf portage-snapshot (or is this just a cp of /usr/portage or something?)
generate a new make.conf without PORT_LOGDIR, PKGDIR, etc.
Install user-selected packages
ln -s /usr/share/zoneinfo/x /etc/localtime (optional)
uninstall toolchain and portage (other unwanted stuff too)
	TIP: To unmerge portage, use equery files portage and delete all files and non-empty directories (will have to emerge gentoolkit, then unmerge it once we have the uninstall list for portage)
Package everything - tar/gz or tar/bz2 or one of those and then throw it on an ISO image
Notify the user their build is ready