Extract initramfs from kindle dx kernel image

From Stack Overflow

dd if=/dev/mtd1ro of=uImage bs=1024 count=3584
dd if=uImage of=img.gz bs=1 skip=$$((0x32a0))
gunzip img.gz
dd if=img of=initramfs.cpio.gz bs=1 skip=$((0x14a40))

From http://www.mobileread.com/forums/showthread.php?t=53582