Thank you very much for your patient and nice advice. I follow your advice:
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I have updated the images on the website.
To update an existing one (Fedora 13 or 14), loop mount it then chroot
and run:
mknod /dev/tty0 c 4 0
echo "tty0" >> /etc/securetty
sed -i -e 's/1-6/0-6/g' /etc/sysconfig/init
sed -i -e 's/1-6/0-6/g' /etc/init/start-ttys.conf
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and it really work! Many thanks!

Kevin