I think this project has been dead for a while, most of the activity was about 4 years ago.
I was actually playing with the zf shifter to use with btr 4 speed. In the end i've used the ugly 4 speed quadrant shifter and written my own program on a microcontroller to signal shifts to the TCM. I have the option to use flappy paddles, and i might use the mode and cruise buttons on my FG steering wheel to do that, but i haven't yet.
As for your question of linking directly to the TCM, i don't think it will be easy, because i think the chips on the shifter circuit board will be making a serial connection to the trans controller and sending streams of data. But, I haven't played with the FG so i don't really know. The ideas being thrown around in this thread were really just looking for the simpliest way to emulate the action of moving the tiptronic shifter.
Good luck, i hope it works for you.