First, put your mayo in a bowl, then add lime juice. You may think you are watering it down, but when you add the cheese it will look right again. =)
Next add parmesan cheese, don't be stingy! It should look really grainy when you stir it together.
Next add the cayenne pepper so that you can see how much you're adding while it's still white. This totally depends on your taste, add a little or a lot.
Now stir in the chili powder, keep stirring in more until the whole bowl is a light peach color.