I believe the OP is referring to the "livecd-creator" and not the "liveusb-creator" and if so then you will have to have "livecd-tools" and "spin-kickstarts" installed. Then open a terminal as root (su) and enter:
Code:
livecd-creator --config=/usr/share/spin-kickstarts/fedora-livecd-desktop.ks
and that will create a livecd.iso of the Gnome 3 desktop with the latest updates.
You have to be patient when you first run the script as it takes a while for the livecd-creator to gather info for the creation of the new iso.
phil