progeCAD can read and use Microstation .dgn format as underlays. However I can confirm that there are no plans for progeCAD write DGN files. As we understand it, Microstation can import a DWG or DXF file from AutoCAD (or progeCAD) already.
progeCAD support, tips and troubleshooting forum. progeCAD works very similar to some versions of AutoCAD. Moderated.