Bootable CD w/OS for firewall

[lug at the-leveys.us (Don Levey)]

So here's a question that's probably been beaten to death long ago, but I
just can't find the information in a form I can use.

I wand to create a bootable "live CD" for my firewall.  Basically, I want to
keep all the configuration static, and if I need to change the rules, I'd
burn another CD.  Part of the twist is that I want to have a small hard
drive around for /var to keep logs, and whatever state info needs to be
writable.

I've found a few "roll your own" links, but they either don't seem to
address what I need, or I don't understand them.  Anyone have any links to a
write-up for this sort of thing?

TIA,
 -Don