As I have posted in some other posts/threads, this conversion will require cutting the cars rear floor panel (part of rear passenger seats and part of the trunk) and re-welding a AWD (EVO or Lancer GSR) floor panel with the AWD fuel tank back in place.
Since the FWD Lancer fuel tank and floor panel will not aollow the rear transfer case and the drive shaft to fit, you will have to do such procedure....
To get the parts, it's not that hard and expensive; however, the cost of good quality labor will be high. You will need to line up everything perfectly in order for the car to "drive right"....
You're in Brazil, right? I don't know how much would that cost then....
Hope this helps