VAG-COM compatible OBD reader

[masster]

Hi
I have this OBD2 interface: http://www.scantool.net/obdlink-ci.html and I have been told that with reasonable effort can be modded to be recognized by VAG-COM (VCDS) software from Ross-Tech (http://www.ross-tech.com/). Basically it is about connecting one more pin of DB9 connector to existing circuitry.

I couldn't get the schematics of my interface, all I can do is to show you the front/back of the PCB (click for high resolution photos).

Can you guide me to mod it, please?