?'s from a buick owner

Okay, heres the deal. I've been reading about Park Avenues having 6 speaker systems(2 in door, dash and rear). Is it possible to mount the 5 1/4" in a 92 buick with no door speakers since its basically the same car? Then if its possible, would i just splice into the front speaker wires to run them and then run the wires?

Thanks