you cannot boot into os 9.x with that ibook. This is due to a firmware-"protection". Anyway, I am sure there are some hacks out there. If you don't want to change the firmware (which I would suggest), you gotta stick to oxs and classic..
Y do u want to go back to OS 9 anyway? surely there is an app in OS X that will do the same and theres always clasic - although not recomended for day to day use!