um......i'm not sure if thats a smart DIY project......you'll have to cut a hole in the roof of your car, wedge in a pocket for the roof to roll back in (which will probly mean you have to pull the interior roor back and cut several inches of headroom from the passenger compartment), put in a motor with railings for the roof, and to make it all happen you'll need to be wiring switches to the motor and power supply.
oh, and dont forget getting gaskets and stuff to seal it all up with. you dont want a leak.