Mac Keyboard Driver on Windows 7 - Trully configure fn and media keys (or forcibly installing BootCamp)

Question

I did exactly the same as the OP of How do you reset Windows keyboard drivers to their original defaults? at first (kudos for Being the very-smart, highly-intelligent person that I am (</sarcasm>)).

I could install the driver with success by downloading Bootcamp installer and running BootCamp5.1.5621\BootCamp\Drivers\Apple\AppleKeyboardInstaller64.exe which made my F1-12 to be usable only by pressing FN (so media keys are the 'default').

But reading Change function keys in Windows 7 (bootcamp), I wanted to give a shot by installing full bootcamp.

So I did (tested that with BootCamp 4.X and 5.X drivers and installer):

1. Used BOOT CAMP X64 IS UNSUPPORTED ON THIS COMPUTER MODEL – SOLUTION to fix the 'unsupported device' problem;

2. Fixed the Administrative rights problem with .msi files by browsing the folder with cmd and then typing msiexec /a BootCamp.msi (if run by double-clicking, says needs to run setup.exe but I can't configure the .exe like #1 suggests for .msi, there's no 'skip version check' on the 'Windows compatibility mode' list);

3. After running (with no prompt of whatsoever), shows the following message:

4. Tried both resetting when it requests as well as resetting later: Nothing changes, no Control Panel -> System -> Security -> Bootcamp or Control Panel -> Bootcamp or anything to bootcamp related on CP or Start.

The million dollar question(s):

Is there any way of forcing BootCamp CP to install so I can use the lovely Use all F1, F2, etc. keys as standard function keys?

Or a registry entry I can add to fake that setting toggled on?