I have created and installed Fedora live-cd images to usb devices, mainly 1-2GB in size. Also when the F9beta was released I too was very interested in the "persistence" aspect of a usb install. I have installed the Gnome desktop release first and just today d'loaded and installed the Rawhide F9 KDE live image and installed it to a 2GB usb device and currently waiting for 61 updates to be installed.
I will reboot when finished and see if "persistence" is working. I have run into a couple of problems with the Gnome F9 beta during updating hopefully KDE gives a better showing.
Well now to the original post:
I wasn't able to install to a usb device and create a "overlay" for persistence when I tried to run this script:
# livecd-iso-to-disk --overlay-size-mb 512 Fedora-9-Beta-Live-i686.iso /dev/sdb1
then with the help of google I found this site at this link JeremyKatz
then I grabbed the "livecd-iso-to-disk" script from the link on the page and then ran the script with the arguments mentioned for my install:
# ./livecd-iso-to-disk.sh --overlay-size-mb 512 Fedora-9-Beta-Live-i686.iso /dev/sdb1
then the image was written to my usb device.
I had placed the "livecd-iso-to-disk" script in the directory containing the live-cd image then opened a terminal there and ran the above script and arguments as "su" and the install proceeded. I have also used the same usb device to install the rawhide F9 KDE image and the script removed and over wrote the previous install.
EDIT: well the "update" appeared to go well and while running from the usb device before during and after updates seemed good and now the "but" part upon rebooting got this message:
Bug in initramfs /init detected. Dropping to a shell. Good Luck!
same problem experienced with a Gnome beta also.
EDIT 2: Have reinstalled to the usb device and added a couple of packages and made a few minor adjustments to the desktop also edited and saved a couple of screenshots and upon rebooting changes were "persistent". My experience with the usb installs has been that when an update of packages has been made there may be a very good chance that the usb device will no longer boot. Just for the purpose of checking out KDE4 and some of F9's features it works well.