Hey Dnk
The easiest but unfortunately expensive is programmable control system. Lutron Homeworks etc.
However I did the exact same thing for a Radio Ra system I installed last spring. I'm gonna assume you dont have either a control or Ra system, so I'm gonna adapt my solution to [can't believe I'm saying this] X-10.
Install a hidden 12*12*4 pvc pull box away from the pillar. In it use an x-10 switch to control the load. On the same circuit mounted to the cover of the pull box use a Leviton x-10 photocell. It is adjustable to shut off after x hours. In parallel with the x-10 switch install a relay. Control that relay with the driveway pillar sensor. In line with that sensor install a standard photocell if needed so as not to turn on lights during day. This last one I needed to do because we used a standard driveway sensor with no settings. If I can find pics i will post for you.
