The BIOS from this machine certainly indicates that it can boot from CD, but it consistently displays the messages 'Non-system disk or disk error.'. The target machine is the only machine that I can test the boot-ability of the burnt CD is a Compaq Presario 5320CA (circa 2001). That being said, I'm not certain the problem is with the burning process. As none of those attempts have proven successful, I won't repeat the details here.

copying the files, creating a read-only image from the contents of the ISO, etc.), and then burning those. I've tried both methods of burning the ISO.

I am downloading the images (install47.iso, cd47.iso and cdemu47.iso), and trying to burn them with Disk Utility, which I presume is the same as the Finder 'Burn' command when you right-click on an ISO image. I suspect the problem lies with the burning process with Mac OS X. Unfortunately, the expected route to success, download + burn with Mac OS X, does not result what seems to be a bootable CD. I'm trying to make a bootable OpenBSD CD image on Mac OS X Snow Leopard (10.6).

Mac burn iso disk utility