Try this:

Issue: Upon booting DVD installer you see a message "waiting for root device…" This is a known issue that comes up quite frequently. Your IDE or SATA chipset may not be supported by the installer. Unfortunately there is no easy fix for this problem. You must have a working install of OSX to do this.

Solution 1 Find a known working kext for your specific chipset.(Google is your friend)

hdiutil attach /"Leopard.iso" -readwrite

Create a folder named Extensions on your Desktop
Unpack Extensions.mkext from the Leopard.ISO in this folder
mkextunpack -v -d /Users/"YOU"/Desktop/Extensions /Volumes/"Leopard.ISO"/System/Library/Extensions.mkext

Remove the MeDevil's kext(AppleNforceATA.kext)
Replace with the one known to work for your chipset
Fix the permissions on your new file
type

kextcache -a i386 -K /Volumes/"Leopard.ISO"/mach_kernel -m /Users/"YOU"/Desktop/Extensions.mkext /Users/"YOU"/Desktop/Extensions

and place the newly created Extensions.mkext into the ISO and burn it to DVD and try again.