GL Lines Occlusion Culling

I am currently drawing GL.LINES on top of my camera which renders the scene to avoid some graphical errors (Lines run along surfaces) and so they can be rendered through objects. However i want to be able to selectively disable the rendering of the GL.LINES when they are behind an object. I have tried ray casting, however this doesn't account for a partially visible line. What i want to be able to do is have a separate object on a layer that only on the GL cam renders that will block lines that are rendered behind it however it is not rendered itself by the camera, so basically occlusion culling.

Is this possible?

Thanks, Ken