They will be multisession, because they will hold at the least 3 images as mentioned above. You should be able to extract each session from the CD image with something like ISO Buster and then mount the powerpc bigendian BFS under BeOS on your BeBox. If you can get that far, you can burn that image to a CDR under BeOS PowerPC and I believe it will boot. I did it years ago, but I don’t have access to any of the tools I used at the moment so can’t confirm anything.
You might also want to try burning the image at a slow speed, because the SCSI CDRom drives in older hardware often have trouble reading modern discs. You could try this version? Help Installing Bootable BeOS 5.0 Professional PPC