first you need to degas the system (by law the gas is suppose to be kept not let loose in to the air), then you need to remove the a/c pipes, wires and compressor bolts (there should be 3 of them) that hold it to the engine. Then to reassembly just do it in reverse, but you will either need special tools or some one to regas it for you. Or you can just get some one who has all the right gear to do it for you.