Here is my workflow:
1. Use the Vegas 'Import From DVD' tool to bring all the VTS files onto a new timeline. It was originally an auto-play DVD with one 1 hour movie.
2. Use Vegas to generate the Title Card.
3. Use Vegas to export the Title Card and VTS clips all butted together.
4. Use DVD Architect to create a new DVD.
Seems like a lot of re-encoding but is there a better way?