Not sure how soon you need the info, but im putting a new JVC double din headunit in my VZ this weekend. So im still fresh with info.
You'll need the adaptor mentioned above for the radio. You WILL need a harness too. The VZ wires coming into the head units are in 2 main plug packs. Your input on the Kenwood is one plug pack. So they wont go together. I bought from autobarn a 'VZ wiring harness' (Aepro) which plugs into the holden plugs (2plugs to 2 plugs) then a 'JVC harness) which put the 2 Holden Plugs down to the JVC plug that bolts in the back of the HU. You dont need the second one as you can always solder the Holden one to the wiring harness that came with the Kenwood. But for 25 bucks or so I got lazy. To reiterate, there are TWO output plugs inside the console of your car, there is ONE input plug on your headunit. They need to mashed together, to do that get wiring harness. Dont ask JB they know nothing, they just sell boxes, the autobarn guys at my local store were great. I can illustrate further if you like. My Head Unit is in, tomoz its the speakers.