Using the the Fedora LiveUSB-Creator i had no issue installing a pre-downloaded version of the F15-KDE-Live CD after browsing for it in the download folder.
yum install liveusb-creator
An Icon will be placed in "System Tools", looking like a blue usb stick.
Heck, i even made the first 128mb of this 1gb stick a dos partition, but the 2nd partition (~ 920mb) ist ext4 with bootflag enabled
Not sure about how i installed the "extended settings", i think it was with the command "sudo yum install gnome-tweak-tool".