I've seen it done using bobcadcam. I'll try to find the video. Did the same to extract profile for lathe work. Basically a plane (or several planes) is drawn cutting into the solid model. The intersection is then taken, leaving behind the slices required.
Add: This is the video:
3G was acting up. Couldn't play the video to confirm earlier. I can't recall if BobCad can export to DXF. Will check when I get home.
Regards,
Wong
edit: embeded link ds