I went as a walk in candidate for PLDC last month here in Korea. I didn't get in but I figured I'd post some tips for getting if you asre a walk-in.
1) for the first formation on day zero and every formation until after the weight and tape, fall in as far to the left as you can. I was in like the 3d file and thought I was high speed, until we started inprocessing and they gave the command "left face" and started inproccessing from the opposite. I was doomed from then on.
When you get to the auditorium, again sit to the left. If you are nonpromotable like I was, dont say so even if they ask. they wont know the difference and youll get in. Any time there is an empty seat further to the front of the auditorium get up and move to it. When you are told to move up, and this may sound ridiculous, move with a purpose, knock people over, elbow your way through. There is ultimately one E8 that decides who gets in and who doesnt. He is constantly watching the soldiers (and I MEAN constantly) and he likes that sort of thing. be cut-throat and show it. good luck!