So, after using tazusb in order to successfully create a live usb, i've tried to install it persistently on the same usb, formatted as ext4 , label "/" , flag bootable + a linux-swap (sdb1 and sdb2). No errors appeared in meantime. Then i've tried to boot, but it didn't recognize the root, so i had changed root(hd1,0) to root(hd0,0). At this point the system will go next, but just to stuck after errors like "sending discovery", "sda:no caching file", "no such process found" etc...
That's the menu:
# /boot/grub/menu.lst: GRUB boot loader configuration.
#
# By default, boot the first entry.
default 0
# Boot automatically after 8 secs.
timeout 8
# Graphical splash image.
splashimage=/boot/grub/splash.xpm.gz
# Change the colors.
#color yellow/brown light-green/black
# For booting SliTaz from : /dev/sdb1
#
title SliTaz GNU/Linux 5.0 (Kernel vmlinuz-3.2.53-slitaz)
root (hd1,0)
kernel /boot/vmlinuz-3.2.53-slitaz root=/dev/sdb1 quiet rootdelay=9