Line breaking

I have a qustion. I want to make a wireframe box in openGL, and need the back lines to be 'broken' by the front lines.
Here is an image showing what I mean. (http://templeton.gt.ed.net/~eric/question.jpg)

I don't need actual code to do it, as much as an explanation of how to do it. I know that I need to use depth testing with some wide clear lines, but am not sure how. Any help at all is greatly appreciated. Thanks!

Eric

[zed]

im not certain if this'll work
but u could render the box with thicker white lines and then render after wards with thinner black lines.
make sure the depth test is set to LEQUAL