This is probably one of the most important moments in my project's life so far.
In a few words, the dashboard now reflects the exact state of the simulation in Live For Speed, covering for the moment only the control lights.
So, this is what I've done recently.
First, I've ported the original software to the Arduino language and flashed it to the new board. Hooked it up to the dash interface, and voila! The lights were flashing in sequence just as before.
This encouraged me to go to the next step, so I modified a C# code that I had previously found on the web, which connects to LFS using OutGauge, to acquire live data on a UDP connection. I modified this program to send all the data through a serial port to the Arduino board.
The updated Arduino software continously reads data from the serial port (simulated over USB), interprets it, and sends the corresponding signals to the dash interface in order to light up whichever control lights are on in the game.
All of the lights are working, such as turn signals, hazard lights, full beam, traction control, parking brake, shift light, and red line.
Here's the thing in action.