There is no DB schema because there is no real database. You could try to parse the TDT format, but it's an internal format and would prove difficult at best. It really is not meant for external consumption.
So, technically, yes, the only way to do this is to "Load, export", wash, rinse, repeat. Adding a way to do this is not really feasible since it's the very rare user who needs it. It isn't a good use of my time. But having said that, sometimes wiring something up internally as a one-off might not be so bad (many times it's making a feature nice and pretty and flexible and usable that's hard). So, if you want me to try to perform the "Load, export" steps for you, I *might* be able to. Assuming you want it dumped in one of the existing XML export formats.