Show object under another as a dash using class override

[CS1]

Im pretty sure this is asking to much but its worth a try.

If I draw two squares or extrusions, and have one lapping over the other slightly, is it possible to use a class override or something so that the area of square that is under the other shows up as a dash?

I also have a small rock which I am trying to extract a small amount of blood from can anyone help.

[Guest Wes Gardner]

My understanding is that things 3D cannot be shown as dashed. What I do for beams, etc. overhead is make a hybrid symbol with the extrude being the 3D component and let's say a rectangle (dashed line) making up the 2D element - combine into Symbol and voila!