And after you've burned the CD, insert it into Mac, reboot and press C key from keyboard to get it booted from the CD. Alternatively you can press ALT key to get into boot menu and use arrow keys there to select the CD and press enter to boot from it.
After it you can use it as Live-CD or install the OS to HD.
For more info about MorphOS read MorphOS.readme, MorphOS Team's web page and
http://www.morphzone.org/library/
