Try this for start:
/usr/ports/sysutils/freesbie
Code:
# cat pkg-descr
The FreeSBIE port is a collection of scripts which
help a user to create CDs/DVDs containing a complete
operating system based on FreeBSD.
It is used as "live-cd" and boots straight from CD.
Consequent use of filesystem compressing techniques allow to
include a huge number of applications on a single disc.
Creation of the CDs/DVDs is completely dialog based as well as
building and installing of packages.
For further information, please visit the official homepage.
WWW: http://www.freesbie.org/