I'd go ahead and use the edge of the pad, but I'd be a little careful about it. The PC isn't like the rotary and I've never had any problems doing stuff like this with it.
Oh, and while you gotta be careful about what products you use, I polish taillight lenses with the PC and my regular polish all the time, no problems. I got mighty aggressive with the Blazer's taillights and they turned out surprisingly well considering how bad they were when I started.