Hi,
May I'm missing something, but another alternative could be create a DXF file "by hand", starting with a "smart" DXF template (predefined blocks, styles, layers,etc) , it's not that complicate to do so, and it doesn't requires any other software, only AutoCAD for the template creation and testing. However this solution goes from very complicated to impossible if you need solids or surfaces to represent the final result.
Gaston Nunez