If I remember rightly Awesome GTI were flogging some smooth boot plinths some time ago.
All you would have to do is fit a solenoid to the tailgate that had a 12v feed, and a switch placed somewhere in the car. I did this to my old Jetta, and I had the switch in the centre console away from prying eyes. The only problem was that you had to open the door to get to the switch to then open the boot to put stuff in it.
As regards the central locking, you can buy universal kits that are a doddle to fit, they retail at about ?50-100 depending on how many doors you've got.