It is not possible to move the LiveCD of 2006.1 onto a USB device to create a LiveUSB boot device. The USB driver support seems to be missing in the initial kernel that syslinux boots. http://www.gentoo.org/doc/en/liveusb.xml 2006.0 seems to work fine.
It has nothing to do with the drivers being missing. *** This bug has been marked as a duplicate of 147186 ***