CET Designer can export several formats of SIF files from their calculations screen.  Once that SIF file has been exported you can open that SIF into Worksheet or ProjectSpec.  The only thing to consider is that if you have placed or converted blocks with our ProjectSymbols extension, your SIF file will be using the pricing that has been supplied by ProjectMatrix and would be consistent with ProjectSpec since our catalogs are typically more current than that of 20/20 with the use of ProjectNotify.