Training text-davinci-002 with custom code

While I am waitlisted to get access to Codex private beta, I am exploring the capabilities of text-davinci-002 in understanding code. I notice it is pretty good in understanding simple python programs and providing descriptions/comments.
Is there a way we can train text-davinci-002 with custom code, the same way we train it with text corpus.

Finetunning text-davinci-002 yields better results for many cases. Just need to be more focused, and feature engineer it towards your specific application.