Upload Pre Transcoded flavours via API

Hello All
We have rebuilt our Kaltura server from a very old version 6 to a shiny new v12. We have over 1200 source video files alone and have estimated that the time to re-transcode those on the new server may be 1 month !

Currently I have developed scripts that query the old server database, create the xml to bulk upload the source media, Query the old server API for the existing custom metadata, inject the custom metadata into the bulk upload xml. What I really would like to do is also upload the transcode flavours from the old server.

Is this possible ?

I have already read the thread API to upload video without using KMC.
Is it possible to use the same FTP method that is used with XML Bulk upload via KMC ?

What I would like if possible is a bit of a step by step break down