Installing Wheezy from an iso image on a USB stick booted via grub2

[Adam Wolfe <kadamwolfe@gmail.com>]

I've done this several times without issue using other debian 
derivatives but for some reason wheezy fails at installation when 
attempting to detect the disk.

below is the menu entry from my grub.cfg.  If anyone has any tips it'd 
be greatly appreciated.

menuentry "Debian Wheezy amd64" {
set isofile="/boot/isos/debian-testing-amd64-CD-1.iso"
loopback loop $isofile
search --no-floppy --fs-uuid --set=root 674E-E67D
linux (loop)/install.amd/vmlinuz append video=vesa:ywrap,mtrr vga=788 
iso-scan/filename=/boot/isos/debian-testing-amd64-CD-1.iso noprompt 
noeject toram=filesystem.sqaushfs findiso=$isofile
initrd (loop)/install.amd/initrd.gz
}