Hacking priiloader warning: "unmodified IOSs!"

[gcb]

on the priiloder page http://wiibrew.org/wiki/Preloader/Priiloader
what does the warning about unmodified IOSs even means?!

It is highly recommended to install Priiloader only on a Wii with only unmodified IOSs!

That means only the <57 IOSs right? or does the cIOs on 58, 222, 223, 249, 250, 251 counts? if yes, i'm not sure i understand how i should even install it