Elroy, correct. This project does not automate building SxS manifests. It is designed for automating application manifests. Though one could use this project to create a SxS manifest but that would be difficult because one would need to fill out all the XML attribute values manually, knowing which ones to add to the manifest. This project was not designed for automating SxS manifests and don't ever expect it will be. The closest it comes is its ability to load an existing SxS manifest, edit it, and export it.

I think there should be a FAQ page or Tutorial on ways to create SxS manifests correctly and completely. That FAQ/Tutorial could include custom tools others have designed and/or usage of existing APIs and/or Windows apps.