I've gotten DXF files out of Doga into Amapi, Blender, and others, Try Crossroads3d:
EDIT, The crossroads 3D site is down.... google for it maybe. If I can find it I'll send it to you, it was a freeware.
Amapi:
http://www.amapi.net/amapi.php?va1=ZG93bmxvYWRz