From Justin.tv API Wiki
Creates a new user with a channel. This call is restricted to whitelisted applications to prevent spam. OAuth tokens for the created channel are returned.
- birthday (yyyy-mm-dd format)
- category and subcategory (see Justin.tv Categories)
- Can additionally include any channel parameters that are not read-only. (see Channel Object)
- In order to upload a picture, set the content header 'multipart/form-data' and send a valid jpg, png or gif in the picture param.