dyfedpowys1104

i am new to this, have not yet played it but i am getting gta iv in next day or soo.. and i was wandering just how easy is it to put all these different things on, as i am from wales i want british police cars, and to be as relistic as possible, already seen good ones such as speed camera's number plate readers, breathalisers, tasers and things like that, but how easy is it to put all that into the game ? thanks