I assumed a 2.6 kernel for some reason. My previous post will work for reading but not for writing.
If Slack auto configures a writer using scsi emulation then the device will be /dev/scd0. The quickest way to see if it is configured via the cdrecord command:
If that does not show any devices then you will need to add a line to your bootloader configuration file. I believe the default is lilo i.e. /etc/lilo.conf like the following: