All mod chips can via a CD burn if you can't from a USB device, I would just presume you can't boot a USB device and go with the CD-R option
All PS2 mod chips do this every time it boots a CD-R/DVD-/+R all PS2 games use elf files to boot from
If you go with the CD-R option make sure you dummy it up, just add some random files to your CD to fill it up a bit, this just makes sure the CD is read ok by the PS2, extreamly low toc PS2 CD's and DVD's can have reading problems, you could even have one of your compressed PSone CD images on there as a dummy file to fill the CD up, the CD does not need to be full to the brim but atleast half full should be enough for it to read ok by the PS2 (this is more for CD's with minimum files for booting ulaunch, for the softmod install/PSX exploit)
]
