first of all, my english is not perfect, i speak mostly spanish, so this can be a little confusing.
I got a okami.wbfs file (ROWE08.WBFS), and a Fat32 8gb usb drive, i got in my wii sd card wiiflow, neogamma and usb loader gx.
using the wbfs manager, tranformed the usb fat32 drive in wbsf...