Create a scroll view and a grid under your scroll view. Create a single child item for what your entries should look like (even a label will do). Make a prefab out of this item then remove it. Make a prefab out of the scroll view, then also remove it.
Don't use UIPopupList anymore. Instead, create a button. When the button is clicked, NGUITools.AddChild your scroll view prefab, and populate it by instantiating your item entries over and over, filling the list.
