It seems the only way to create Netcad drawings (*.ncz) from DWG CAD sources would be to use Netcad itself, because no other software otherwise supports NCZ format.
Convert AutoCAD drawing to Netcad drawing.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert dwg to ncz on Windows
Old CAD and GIS software
Convert from dwg file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.