Do you have an image of what you are trying to achieve?
The ‘going past’ is, I suspect going to be the real issue. All normal CSS borders meet at 45 degrees and don’t cross.
There is an option which might serve but it involves an image and is not supported by IE called `border-image`.
Its not hard (but not easy either) and, as I said, you would have to have an image of the whole border.