Driver side wiring harness removal....

Can anyone give me a breakdown on where/how to remove the wiring harness for the doors electrical components? The door is no problem for me, but where do you disconnect the wires that connect in the chasis of the car? Do I have to take an interior panel off, go under the car, or through the engine compartment (please tell me it's not the engine compartment! :-( )? I'm all set to do the splicing of the wires, I just need to know how to remove them from the car itself. Thanks to anyone who helps me out on this one!