I have to make a confession, I do not have PSCS and the last time I used the full Photoshop it was PS 5.5 in 2000. Although I recently acquired PSE 12, I still prefer doing much of my "after-LR" in the pixel level editor I have been using for the last 14 years, Picture Window Pro. And PWP has a perspective correction tool (called the "Warp Transformation") that works very much like what the OP described using in PSCS - a crop box on which each corner can be dragged independently in order to align a grid overlay with image lines. I assumed the tools were the same. (PSE's correction tool has a slider interface similar to LR's.) I find that method very fast, while in LR I need to spend many minutes finding the right combination of Vertical, Horizontal and Rotation slider values, because frequently a change in one of them requires a compensating change in the others and I go round and round and round again.