- unpack the sources of the portage to use
- run (adapt prefix/offset-prefix arguments):
configure \
	--prefix="/home/prefix/rsync-master/scripts/prefix/usr" \
	--with-offset-prefix="/home/prefix/rsync-master/scripts/prefix" \
	--with-portage-user="`id -un`" \
	--with-portage-group="`id -gn`" \
	--with-extra-path="/bin:/usr/bin"
make install