Installing Lenny armel in USB thumb drive by Qemu.

I used netboot image.

$ qemu-system-arm -M versatilepb -kernel vmlinuz-2.6.26-1-versatile -initrd initrd.gz -hda /dev/sdb -append "root=/dev/ram"

next first boot

qemu-system-arm -M versatilepb -kernel vmlinuz-2.6.26-1-versatile -initrd initrd.img-2.6.26-1-versatile -hda /dev/sdb -append "root=/dev/sda1"

initrd.img-2.6.26-1-versatile is extracted from /boot/ of usb thumb drive.