how to install into a directory

[hw]

Hi,

how can I install FreeBSD into a directory as [1] suggests:


"Install the base system into ${NFSROOTDIR}, either by decompressing the
official archives or by rebuilding the FreeBSD kernel and userland"


What archives is this referring to?  Could I run the installer to
install to a hard drive until I have set up everything the way I need it
and then boot from a live-CD to copy everything from the hard drive into
${NFSROOTDIR}?


[1]: https://www.freebsd.org/doc/handbook/network-diskless.html