Doesn't really matter which of the field terminals gets the blue and which gets the green wire, but yes. So you will want to disconnect both wires and make sure neither terminal on the alternator is shorted to ground. If you don't have a multimeter, use a test light with one end on the battery positive terminal and the other end on the alternator terminal to be tested with the alternator on the car; it shouldn't light up (but should light up with one wire on the battery positive and one on the alternator casing).