I have been working on getting the depth buffer to generate properly and using it to post-process the wires (i.e. creating the outline around the wireframe) and so far I'm quite satisfied...it's still a work in progress, but progress is going well...
This is the result so far, with the depth buffer drawn in the top-left corner and the final image in the middle.
A zoomed-in version of the first image, the effect is visible around the characters head where you see a clear outline being formed, disconnecting it from the other character underneath it.
For comparison I used a color similar to UDK (see first image of previous post)
4 more texture-lookups will be added which adds improved support for diagonal lines - that would bring the total lookups to 14...which is quite a lot for a single effect, but since the geometry will never been drawn with fancy shaders while in this 'mode' (nor any other post-process effect) I don't expect it to be a problem. This effect provides the most benefit when moving around with the camera, I hope to upload a short video of this after I finalized the effect.