Uploading photos to Twitter via WebWorks/JavaScript?

I'm making a Twitter Client for the PlayBook using Webworks/BBui/JavaScript. And everything works great, I can get tweets and post and access pretty much every API call they have.

But I just cannot figure out how to post a picture along with a tweet? The API call (https://api.twitter.com/1.1/statuses...ith_media.json) for it is unique, as it expects multipart data. I can't just send a POST with parameters as with all the other calls.

Nor can I seem to find any ordinary JavaScript libraries or examples for it.

Anyone figure out how to do this?