To start with, you must build an install.cfg file. Here is mine. It was built using the example in /usr/src/release/sysinstall/install.cfg file as a template.
You'll notice that one of the packages (ari-0.0) is not a "standard"
package, rather its a customized package written to configure our group's
FreeBSD machines at the end of the installation process. It contains
the following files:
root/.rhosts
usr/local/etc/sudoers
etc/master.passwd
etc/group
etc/host.conf
And, most importantly, an installation
script. The contents of this script are used to set verious options
in /etc/rc.conf. Things such as enabling NIS, turning
on linux emulation, adding entries for other network interfaces,
adding statically-mounted NFS filesystems to the /etc/fstab file, etc.
To learn how to create a package, read the pkg_create(1) manual page.
Using this method, it takes less than 20 minutes from uncrating a new
Pentium II to having a fully installed and configured FreeBSD workstation
up and running.