[Request] Vaio VGN-Z11WN - Unlock dual graphics switch/advanced menu

Hail masters,
I've a second hand notebook that is amazing except for the linux compatibility. I would be able to unlock advanced features to modify the switch between Intel and Nvidia video cards in bios settings.

I tried by myself with the following tutorial: http://forum.notebookreview.com/sony/473226-insyde-hacking-new-vaio-z-advanced-menu-bios.html
But it didn't work out-of-the-box, I tried to modify the VSS offset searching for the Hex sequence 24 56 53 53... but it didn't work either (and I'm not good in this hacks).

- Notebook model: VAIO VNG-Z11WN
- Os: Windows Vista
- Bios version: InsydeH20 Rev. 3.5
- Bios download link: http://www.sony.co.uk/support/en/content/cnt-dwnl/prd-comp/EP0000209810_4736/VGN-Z11WN

Please, help me!

-- Edited
Added BIOS screenshots.
Added BIOS dump obtained with 'flashit.exe' tool.

  IMG_20141122_162709.jpg (Size: 109.96 KB / Downloads: 1)

  IMG_20141122_162720.jpg (Size: 108.1 KB / Downloads: 1)

  DUMP.zip (Size: 950.78 KB / Downloads: 0)