How do you create a linux (RHEL) bootdisk that runs busybox in a ramdisk (initrd)?

I've been trying to create a bootdisk (something like a live-cd) which loads into memory-only without mounting the disk. My steps are listed below, but when I boot using the cd, I get:

Kernel Panic - not syncing: VFS: unable to mount root fs on unknown-block (9,1)

Here's what I am doing to create the boot disk:

1. Create a ramdisk using the mkinitrd tool, then decompress:

   mkinitrd myrd $(uname -r)
   mkdir myrdroot && cd myrdroot
   dd if=../myrd bs=1k | gunzip | cpio -id

2. Git rid of nash, the init (nash script) and modprobe (a symlink to nash)

   rm -f init bin/nash bin/modprobe

3. Install busybox (Busybox is default config, except it's statically linked). Busybox will create a linuxrc and an sbin/init in myrd.

   pushd ~/busybox
   make CONFIG_ROOT=/path/to/myrd install
   popd

4. rebundle the inird:

   find . | cpio -n -o | gzip -9 > ../myrd.img

This ramdisk is then used with ISOLINUX on a CD. I copy over the kernel that matches $(uname -r), and configure ISOLINUX to boot the kernel with the ramdisk.