The key is teaching this drill.
Have the forwards skate as fast as they can, but instead of just skating right at the D, they have two options by the time they get to the cone...1-2 strides to the outside, and then 2-3 strides to the inside and cut in.
Or 1-2 strides to the inside, then 2-3 to the outside and cut around the D.
Key points:
Get the D moving his feet.
Option 3...if D cheats...instead of going just 1-2 strides, if D doesn't move, make it 3-4 and beat him in that direction.