Uh, that's asking the client to read something it's not designed to read? Go redesign the client to read the .csv file then. Then, you'd have to make sure the client knew what to do with the data.
1. If this was easy, it would have been done a long, long time ago. And, this is just plain crazy btw.
2. The client only reads certain .csv files.
3. You can't add things into data.pak. You can only "replace."
These reasons are why we only edit data.pak and/or .csv files. We don't create or add anything.