Hello Ritesh,

There have been many a cry of anguish regarding the additional micro controllers to this otherwise very user friendly application.
I am not sufficiently clever to do this on my own but sometime ago have had some guidance from the author of the application ( to no avail obviously, I am that kind of a guy).
You may want to consider the possibility of generating C file and then going via Arduino to program the unsupported atmega chip(s) .

A search for Arduino process is mentioned in one of the threads.
In the mean time check out the following link; it will take You through a number of threads and discussions on adding new micros.

Good luck and keep us informed of Your success.
http://cq.cx/ladder-forum.pl?action=viewthread&parent=3341