GROMMET TROUBLES

hello Everyone,
I have a set of brand new P5007611 Black Wrinkle valve covers.
I have the two grommet's for the PCV and Vent Cannister.
How do you cut the holes in the valve cover for these to fit? Each Valve cover has a oil fill cap so those stay. I am concerned also about the hole size for the vent.?
Any suggestions?