One thing you can do in wa is the zoom thingy in the "display"-options. Maybe not exactly what you are searching for because after zooming in the icons have no border at all :>
WeakAuras doesn't integrate with any addon like masque etc and it's not particularly high on the list of things to get working. You can add borders to groups but that's probably not that useful to you. The best way to get custom borders on icons is to use textures instead of icons (because you can draw your own and import them with shared media) or to replace your icons entirely using one of the icon packs on wowinterface (ie: clean icons thin).