Not sure if the vx one will be the same as the vs but this is how to do it on a vs. Firstly, turn your acc. on to give the stereo power. If the code needs to be put in, teh stereo wont do anything when acc. are turned on. Just punch in the code on the number pad. Each time you press a number, it should show up on the screen. Once you have put them all in the stereo should come to life.
Its as easy as that on the VS's so hopefully that will help you get yours going. Otherwise someone with a vt/vx should be able to give you a better answer