I haven't performed a thorough analysis of the rules in that guide, but one thing that quickly stands out is:
Code:
firewall_type="/etc/firewall.conf"
I believe that should be:
Code:
firewall_script="/etc/your_ruleset_file_here"
The FreeBSD Handbook has a section on IPFW:
28.6 IPFW
Be patient and read through that; you should be able to glean enough to put together a basic ruleset.