Is your trackpad compatible ?

First, you have to know if your trackpad may be used for two fingers scroll. You'll have to execute the following command line:

ioreg -l | grep "W Enhanced Trackpad"

What must be downloaded ?

If the previous command line returns "W Enhanced Trackpad = 1", then your trackpad may be used for two fingers scroll, and you can keep reading. Otherwise, do as you wish, but it will be time wasting.

Your trackpad is compatible. Go there, download one of the available drivers (i.e. iScroll2_all.zip), and unpack it into you home folder.

How-to install it ?

First, you have to unload the running trackpad driver. Execute the following command line:

sudo kextunload -b com.apple.driver.AppleADBMouse

Now, do not touch your trackpad if you don't want to see a nice Kernel Panic. Then backup your old trackpad driver with the following command line:

sudo mv /System/Library/Extensions/AppleADBMouse.kext /System/Library/Extensions/AppleADBMouse.kext.old

And replace the old driver with the enhanced one:

sudo mv $HOME/AppleADBMouse.kext /System/Library/Extensions/AppleADBMouse.kext

Finally, change the driver access right, and load it

sudo chown -R root:wheel /System/Library/Extensions/AppleADBMouse.kext sudo kextload /System/Library/Extensions/AppleADBMouse.kext

You may now use two fingers scrolling with your trackpad.

The trackpad driver is now automatically installed and loaded.