Hey all, I just updated my transmitter without needing any extra cable, just using my Arduino Nano 
Note: This has been tested with Arduino Nano v3.0, but should work with any Arduino board using ATmega328 like Arduino Mini and Uno. I've also tryed with Arduino Mega, but it doesn't work, seems to work only with ATmega328.
Connections Setup:
- Connect Arduino RESET pin and GND (This will bypass the TTL commands comming from the PC directly to TX and RX pins)
- Connect TX pin from the transmitter to the TX pin on the Arduino
- Connect RX pin from the transmitter to the RX pin on the Arduino
- Same with GND, to GND in Arduino
Connections (see above)
Update instructions:
- Connect Arduino to your PC
- Check in Windows Device Manager for the COM port number assigned to Arduino under Port (COM & LPT), if there is any errors or warnings follow the instructions from the video at the end of the post
- Download the update from http://www.flysky-cn.com/edownload.asp
- Write down all your settings, the update will override them
- Prepare the transmitter for the Update: System > Firmware update > OK > YES
- Execute .exe as Administrator
- Select the same COM port that is in Windows Device Manager
- Press Open Port
If version appears in the text box that means we are connected and ready to update :D
- Press Programme
- Wait until it finishes and done!
Now just disconnect all and restart your transmitter
Enjoy it!!
If you try with a different Arduino and it works, let me know to update the post
Just made a video in Youtube with the main steps: 
https://www.youtube.com/watch?v=LfZHrCZyC6o
Here DalyBulge is hacking this transmitter:
http://dalybulge.blogspot.co.uk/2015/02/ghetto-controller-idea.html
Video to install Arduino FTDI drivers:
