BSD disk images and booting with a serial console

Booting an OpenBSD system with a serial console is pretty easy: enter set tty com0 at either the boot prompt or in /etc/boot.conf. The first won't work in this case. If I had a keyboard and monitor attached, I wouldn't need the serial console. The second seems difficult, given that the OpenBSD boot disks are disk images downloaded from the Internet. But editing those images isn't that difficult. In this article, we'll show how to set up and use /etc/boot.conf on an OpenBSD installation boot floppy. This same approach works on both FreeBSD and NetBSD as well.