To export GDS, you can go to File->Export->Stream... in the CIW.
In the new window that opens up, specify a stream file.
Select the technology library (NCSU_techlib_tsmc02d).
Select YOUR library, toplevel cell and "layout" as the view.
Click on "Options".
Click on the "Layers" tab.
Click on "Load File".
Load this file of layer information: /mada/software/techfiles/NCSU_CDK_1.5.1/pipo/streamInLayermap
Click on "Translate".
Turn in the GDS file.