There are several options for burning a CD in MidnightBSD. If your drive is an IDE drive, consider using the burncd command.
To create a data CD with an existing ISO downloaded from the Internet.
burncd -f /dev/acd0 data disc.iso fixate
This will create a data CD (or DVD) from an ISO file and fixate it so it can be used in other CD-ROM drives.
MidnightBSD also offers an mport called cdrtools. Included with this port is a burn program that can work with scsi drives and anything else that interacts with the SCSI subsystem (USB, Firewire). It also contains a program to create your own ISO images. This port is used to make MidnightBSD install ISOs.