I have the four channel amp running the fronts and rears. If I was to run a sub I would run a separate amp for it alone.
As for the front speakers it depends on if you are going to run an amp.
Without amp:-
Run a wire from the ISO plug (cuting the existing wires as close to the ISO plug as possible) to each end of the dash. Remove the dash end covers and connect the wire to the cutover unit and find a way of securing the crossoversr in there so they do not add to the Coupe rattle and squeak count
The replace the tweaters with the component articles and wire to the crossover. Then finaly run a wire behind the carpet near the door and though the corrugated ruber piping and into the door. This is actualy very easy as the rubber piece unclips at the body and door end and makes it easy to route the wire. Now remove the door speakers and cut the existing wire. You should be able to see the new wire which I connected by soldering rather than those spade conector things.
With and Amp:
Run the wire from the boot down the sides of the car and route to the dash ends and connect to crossover, ensuring it does not run alongside any power cables. Then do the above procedures from the crossover onwards.
Hope this makes sense
Oh yes and don't scrimp on the wire quality
JOhn