It is my understanding you would be using Power'By to access your native SW data. If your objective is to share data between the Design apps and SW desktop then you have to go through a few steps. As you already know, the the design apps are based on CGM and the platform's unified data architecture. You would use an import/export command. I believe a sldxml file is export file type. I'm not very knowledgeable on the SW side of DS, but I recall that there is a 3DEXP PLM service add-in that would alleviate the import/export needs.
Now here is the thing that a lot of people don't get..the 3DEXP platform is not a file-based PDM system. The CAD data is not file-based and this is what throws everyone for a loop. Ah..the end of the world is here..This platform is a unified object-based data model system. In layman's terms, your CAD file is broken out into object-based artifacts in a database. In an enterprise or small company where you have many people who need to utilize different "parts" of a traditional CAD file, you will immediately recognize the benefits of an object-based data model vs. a file-based data model.
I don't dare go any further or be called out as a "sales" or "marketing" guy.