Mike,
I have done this three ways.
1) The easiest is to put a small keep out on the pins you don't want to connect to the plane. I use circle just smaller than the pad. Downfall is if component gets moved later, you have pinhole in plane.
2) Edit pad stack on component to have annular ring with no spokes on the layer you do not want a connection to.
3) Edit pad stack to have oval pads with same height and width on layers you do not want connection to. Go to plane setup options and say do not connect to oval pads.
William