How to reset Toshiba "Satelite" Laptop so it will accept AHCI OS

What I really need is another BIOS for my Toshiba Satelite C70D-B-33K that will allow me to install an OS that is AHCI compatible.
The System BIOS Version that is presently on my Toshiba is 5.10.
Toshiba also says that I should select the CSM Boot mode.

"[CSM Boot] Support to boot non UEFI-capable OS that expects a legacy BIOS interface"

But using that selection, the keyboard is locked when trying to install the other OS.

Here is also what Toshiba says that should be considered:

In order to add the AHCI driver:

Download the latest XP (Intel Matrix) Storage Manager Package from the Toshiba driver download web page. http://pc-support.toshiba-europe.com/drivers/
Unpack the Zip-file and copy the files from the appropriate Chipset sub-folder of the F6flpy directory to a floppy disk as Windows XP only supports adding mass storage drivers from floppy disk.
Connect a USB FDD to the notebook and insert this floppy disk.
Start the XP installation and press F6 when queried.
When prompted "S = Specify Additional Device". Press 'S' and specify select the Matrix driver on the mass storage driver selection screen.
Press 'Enter' to continue with the installation.

CSM Boot does not work for me.
So I then tried changing some data in the Registry in two places, but that didn't help either.
What else can I try?

Thomas