Possible to add sources but not run DVR on Apple TV?

A friend is looking for a live tv solution that has M3U and Locast support for her AppleTV. Doesn't need DVR or TVE. Is there a version of channels for this that doesn't require the full subscription?

No. Streams that don't come from a HDHomeRun tuner must be passed through the DVR server.

For Locast, they have their own app for the Apple TV; for M3U playlists, I believe there are IPTV apps that will play them on Apple TV.