Just as I was preparing to port my code to mbed I've come across this:
The implementation removes unnecessary stuff from the library, so only the SSD1289 Driver is present. This is good for ITDB32S and TFT320_QVT panels. Most functions are coded in assembler, and it runs faster than in the video (It was clocked at only 10Mhz)!
I downloaded the file and made the required changes to work on an arduino mega with the TFT above and adapter shield Elecfreaks "TFT LCD Mega Shield v2.2". Pinout must be similar to other shields and can be found on the attached pdf below "UTFT_Requirements", Arduino Mega/Due Shield (Note: this code does not work in the Due).
Now I will see if I can modify it to drive the display in 8 bits as well.
The code uses some low level functions, not exactly the same as UTFT. There is an example attached, along with the complete library.
Note: Check post #3 for the code