While I haven't tried it, you might be able to copy the data cells from a DB20-G or AT-779UV code plug and paste them into the Ra-25 programming software.*
In any event, writing a code plug from scratch is not that hard, and be sure to keep blank lines between categories (such as GMRS Repeaters, 2 meter simplex, 2 meter repeaters, 70 cm simplex, 70 cm repeaters, etc.) so that you can easily plug in new channels for future growth; instead of having to go back and manually rebuild it from scratch, like I did!
* A feature that certainly would be implemented by CHIRP, if they ever choose to support these radios.