You are completely right, I did not paid attention to the last paragraph (and as the first one is entitled "Old Generation - LS1,LS2,HG,HS" and as mine is an old HS ...)
Anyway, you are right, I had no chance to succeed.
But, I still have a major concern : the given method consist in cloning the partition of the original disc : but what i didn't explained is that this one is dead ... so I no longer have the original partition ...
But with the correct information, I searched for more information and I found this post
that lead to this wiki page : Revive your arm9 box from scratch
And it worked !
the only "trick" is that the installation language is in Japanese ... I then had to follow the official guide to click on the web admin interface in order to set language to "English" (on the left : second tab and then the only list box is the one (and validation is the only button on bottom)
I hope my mistake will help other stunned people