Avira Rescue System

Trying to find a plugin to run the latest Avira Antivirus for my Win7PESE, I came across with Avira Rescue System. It's a standalone ISO based on Ubuntu http://www.avira.com/en/download/product/avira-rescue-system.

I added it to the Gfxbootmenu (I believe it's based in Grub4dos, correct me if I'm wrong) using the ISOImages plugin included in the Project. When selected from the boot menu, the ISO will load and gives the following error:
Unable to find a medium containing a live file system.

Searching online I found a person that claims he was able to fix this problem ( http://forum.bitdefender.com/index.php?showtopic=50064 ), of course he modifies the menu directly.

In his last post he writes this solution:

post Nov 22 2013, 03:47 AM
Russed
 
Good news:
Since I couldn't progress with Bitdefender, I decided give a second chance to Avira. Some years ago, I unsuccessfully tried to boot Avira from its iso. Afters several tries, I gave up. "Self-test failed". Many users also complained about the same in the Avira Forum, but there wasn't any answer. Now they have updated their system. It's based on Ubuntu now, as Bitdefender is. So, I had to search the web for the Grub4dos settings to boot Avira's iso.
Fortunately, a clever German guy found out a solution. I tried it and it worked, so, since Bitdefender is also based on Ubuntu, I adapted it to Bitdefender. Besides of the name of the iso (and the language suffixes de, from Deutsch, German, by the suffixes es, from Español, Spanish), I replaced initrd.lz by initrd.gz in the initrd line. And it worked.
So this is my working Grub4dos settings:

title Bitdefender Rescue CD Lnx32
map /boot-isos/bitdefender-rescue-cd.iso (0xff)||map --mem /boot-isos/bitdefender-rescue-cd.iso (0xff)
map --hook
root (0xff)
kernel /casper/vmlinuz file=/cdrom/preseed/ubuntu.seed boot=casper iso-scan/filename=/boot-isos/bitdefender-rescue-cd.iso -- debian-installer/language=es console-setup/layoutcode=es
initrd /casper/initrd.gz

Say thanks to the German Avira Support.
Besides it is mapped to memory (maybe this is the key), I still can't see much difference with the other settings that I tried before to start this tread, when I skipped the isolinux menu after the kilowog (or Slitaz) style settings failed.
Maybe your can spread the word and add this to the techs notes, for support.
Now I only have to find out how to mark this tread as SOLVED.
One more thing, off-topic. No matter how much I tried, I couldn't enable the checkbox to agree to the license terms. Left-click, right-click, space-bar, enter, escape key, nothing worked.
Best regards. 

My Question is: How can I modify ISOImages or create a new plugin that allows me to boot the Avira Rescue System without errors from the Grub4dos menu?

I'd been having a similar problem and came across your post, which helped me figure this out, thanks.

In my case when attempting to boot to the Avira rescue-system.iso from GRUB4DOS, the Avira rescue environment would open to a splash screen with a status bar.  So, it had begun to boot Ubuntu.  However it failed to an (initramfs) prompt with the error "unable to find a medium containing a live file system".  My menu.lst entry when this error occurred was:

title Start Avira Antivirus Rescue System (rescue-system.iso)
find --set-root --ignore-floppies /rescue-system.iso
map /rescue-system.iso (0xff)
map --hook
root (0xff)
chainloader (0xff)

I searched online for the original solution for Avira referred in your post, but could not find it either, so I took the information for Bitdefender you included and tinkered with it.  The following menu.lst entry worked without any other modifications:

title Start Avira Antivirus Rescue System (rescue-system.iso)
find --set-root --ignore-floppies /rescue-system.iso
map /rescue-system.iso (0xff)
map --hook
root (0xff)
kernel /casper/vmlinuz file=/cdrom/preseed/ubuntu.seed boot=casper iso-scan/filename=/rescue-system.iso -- debian-installer/language=en console-setup/layoutcode=en
initrd /casper/initrd.lz
boot

The versions I am using are:

Making up the rescue-system.iso I downloaded October 5, 2014:
  Avira:  14.12.12.01  (as displayed within the booted environment)
  Avira Engine:  8.3.28.4
  Ubuntu: 12.04 LTS

Booting using GRUB4DOS: 0.4.4 (2009-10-16) on an 8GB, FAT32 PNY thumb drive.

Hope that helps.