Printing without alternating raster angle between layers

I work in a research lab at a University where we have developed a 3-D printer filament made from a composite material. We are interested in printing the material without alternating the raster angle between layers or perhaps eventually being able to choose the angle between layers (as opposed to printing each layer orthogonal to the last). At first I tried approaching the problem by writing a C program to "process" the G-Code generated by Repetier host, but I have been realizing that in order to account for different geometries it would almost require redesigning the wheel as it were. As I understand it the Slic3r program is responsible for generating the G-Code. I have cloned a copy off using Github, but I am not sure which file(s) or folder(s) I may want to look at for this task? If anyone has any suggestions of where I might begin or can perhaps suggest an easier solution to this task I would be grateful.