Hi
Just leaving this here so others might find it in the future.
I just reformatted and installed windows 8.1 - most things work except for the fn+f9 touch enable/disable.
I thought I had synaptics touchpad, since the other one told me I couldn't install it when I used the .exe.
But synaptics driver didn't work together with fn+f9.
To fix this, I got the Touchpad_Sentelic_Win7_64_Z9177 drivers and I went to device manager and updated the driver manually for the touchpad. I chose the driver in the root folder of Touchpad_Sentelic_Win7_64_Z9177.
That made it force install and now it works, yay!
Oh yeah, I have an ASUS G74s!