I don't think it's possible, but thought it was worth asking if it's possible to use the Save to Drive API and have a document automatically converted to the new format? It would be really useful if there was a parameter that we could specify that would allow this. We work with students that are downloading documents that they have to edit. Typically they're in .doc and .xls format. If we could auto convert those documents with the button for our students, it would be immensely helpful.
I did find this issue, but I'm not sure how related that is: https://code.google.com/p/google-apps-script-issues/issues/detail?id=1019