This drills down a few dialogs, but it will do what you want
When symbolizing your layer, pick a polygon style that is close to what you want.
Select Edit Symbol ... in the Symbol selector dialog
Select Outline ... from the Symbol property dialog
Select Edit Symbol ... from the Symbol selector dialog
Change the Type to Cartographic Line Style and select the Line Properties tab in the Symbol property editor dialog. Enter a negative offset and OK out through the dialogs.
You will need to play around with this a bit to get it to appear the way you want.
I would save it as a style once you have it the way you want it.
