Dumb ipnat question

[Michael VanLoon]

I have built a simple 7.1 system in a VM.  I built a custom kernel that is basically GENERIC minus some hardware stuff I don't need, plus a few things that look cool.
 
When I attempt to run the ipnat command, I get the error:
/dev/ipnat: open: No such file or directory
 
Sure enough, there are no ip* devices in /dev/.  In the "olden days", when I used to do a lot of BSD hacking, you used MAKEDEV to make the devices you wanted.  Nowadays, it's done with devfs.  I believe the upshot is that it's supposed to be semi-automagic, isn't it?
 
Anyway, what am I doing wrong?  What do I need to configure to use ipnat and then later ipfw or ipfilter?
 
- Michael