No need for a touchpoint. I've been waiting for years for a capacitive trackpad under the surface of the keyboard. Blackberry have done this on their Passport and it's great. I don't know why others haven't copied the idea.
What about a touchpad on the spacebar. Which such a wide aspect ratio, it might actually work. Or, go back to the double-row enter key and that would be enough space.
How does that work, you run your fingers across the keys lightly or something?
Yes. Two modes: default scroll, means you can scroll without obscuring the screen. Or double tap to get a cursor in a text box.