Booting from CD-RW disc

Hi, I have a PCI card with two SATA ports on Sun Ultra 10, so I can
use modern SATA discs for / file system. I simply specify the
following kernel config:

config netbsd root on wd0a type ?

Unfortunately OpenBoot cannot boot from the SATA card, so I either have
to use built-in IDE controller or the PCI SCSI card. Over the years all
of the IDE and SCSI discs that I hoarded have gradually failed and
nobody manufactures new ones any more.

Below is my boot partition:

ultra10# grep boot /etc/fstab
/dev/sd0a    /boot     ffs     noauto,rw,log    0 0

ultra10# mount /boot

ultra10# ls -l /boot
total 26208
-rwxr-xr-x  1 root  wheel  13287360 Mar 15 16:00 netbsd
-r--r--r--  1 root  wheel    113904 Mar 15 09:51 ofwboot

How can I replicate this on CD-RW disc, so that I can boot from it?
Is it as simple as creating a bootable iso9660? I found these
instructions https://www.netbsd.org/docs/bootcd.html#sparc64image which
I'm going to try in the next few days. But if anyone thinks that's not
the right way to go, then please let me know.

Thanks.