You can easily obtain an MRSS feed for any type of playlist in TargetVideo.
Navigate to the PLAYLISTS section in the CMS, and you will see an MRSS icon next to each of the existing playlists.
Click on the icon, and the following window will pop up:
Grab the URL for the MRSS feed of your choice.
These feeds can easily be used for custom implementations with Roku Direct Publisher and Amazon Creator for Fire TV.