Regarding FreeBSD as a guest:
FreeBSD8.2:
You must have already installed perl, python and xorg via ports. For example:
1) Install BSD 8.2
2) portsnap fetch update
3) portsnap extract
4) /usr/share/ports/perl/make install clean; /usr/share/ports/python/make install clean; /usr/share/ports/x11/xorg/make install clean
5) Download the virtualbox-ose-additions tarball from
http://www.freebsd.org/ports here:
http://www.freebsd.org/cgi/cvsweb.cgi/p ... ?tarball=16) tar -zxvf virtualbox-ose-additions; cd virtualbox-ose-additions; make install clean
This should install vbox additions
7) Follow BSD instructions on Vbox wiki.
==
FreeBSD9
You should be able to build the virtualbox-ose-additions out of the box by following the instructions on the Virtualbox BSD wiki by doing /usr/share/ports/emulators/virtualbox-ose-additions/make install clean
download the virtualbox-ose-additions tarball from here: