Are there plans to provide your own guide data, through a xml file or API?
There are no plans to do this. The DVR requires data in a very specific format with images of certain sizes and required metadata. Many xmltv files do not include all the data we need, and it would require a lot of development effort to handle different data schemas.
Once the DVR is out of beta and officially launched, we can revisit this and find a way to support more international regions.