Yes, I saw some years ago...I think port interface is same as that of ECU but software I saw once was of LANDIRENZO.
At that time, Cng guy at AutoXperts was using that software to rectify the issue of Long start/delay during switching from Petrol to cng at startup. As per that guy, he adjusted setting that car goes from petrol to cng when rpm reaches 2,000 in x minutes.
May be there are other softwares too for such setting