1.4 Use isolinux as the bootloader
Nothing easier than that.

First make a direcory isolinux in the root tree of your rescue system:
mkdir $ROOTFS/isolinux

Copy the kernel image, the gzipped initrd image, isolinux.bin and
isolinux.cfg to $ROOTFS/isolinux

Make the cd image with the following command:
mkisofs -R -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot
-boot-load-size 4 -boot-info-table $ROOTFS > cd.iso

-----<snip>------
# isolinux.cfg 	  	 
  	  	 
DEFAULT 	RescueSystem 	 
PROMPT 	1 	 
  	  	 
LABEL 	RescueSystem 	 
KERNEL 	/isolinux/vmlinuz 	 
APPEND 	initrd=initrdfs.gz ramdisk_size=40960 root=/dev/ram0 	 
TIMEOUT 	100 	 

-----<snap>------

Voila, that's it.