Comment 9 for bug 364538

The script is actually slightly inaccurate as libusual is not a module. But modprobe on the initrd does not seem to print a warning in that case. What was done is to unpack the initrd then look into the file /init and add those commands before the given line.
For a manual workaround it is possible to wait until the boot drops out to the initrd shell. Then type "modprobe usb-storage", wait 1-2secs and then type "exit"
Using kernel-2.6.28-12.43 or later (currently only in the proposed archive) will make this unnecessary as libusual has been removed.