I've got to look at some other trikes to see how they are doing their cabling. I'm kind of stymied at the moment. I put on one cable to the front shifter. So I now have 3 gears up front. But still only one in the back. And no brakes.
I did ride it up and down the street a couple of times while changing the gears up front. Got some pretty good speed. Particularly since I can only use the smallest gear in the back.