This video shows you how to cut the old wheel cover, in detail:

Once you’ve cut the hole, you need to cut the inner part out:

SNIP!

Use a flathead screwdriver to remove the screws.
Note: when re-installing be careful not to over-tighten as this could cause the head to snap off or break the screw all together.

Now you can slide the wheel cover over the cog! Voila!