Oh WOW, i made it at last. This is my way:
I thought i gonna get the "Unknow Hard Error" again, but i didnt!!!!!!!!! I used a whole week to figure out how to do it.... LOL Thank You very much!!
Just for the record, it is basically what has been already described here :
which actually, due to a few shortcomings of the method, originated the "search for a better way", that ended up with the USB multiboot.
Happy you made it, one way or the other.