Using CSVImport to Add Custom Data to a Managed Device's Inventory Data

I'm trying to add Custom Data to the Inventory Database using CSVImport for an already discovered device, but all the information that I can find about CSVImport only pertains to using it to add a new device.

- Would it be possible to use CSVImport to add a Custom Data from a .csv file to the Invetory Data, assuming that I have a unique identifier and the custom data I want to add?

- If so, how would I ammend the template and .csv file entries to search for the existing DeviceName and add the additional Custom Data to that Managed Device's existing Inventory Data?

Thank you in advance for any insight that you can provide into this matter.