In_Wavpack is the Wavpack decoder plugin for J.River Media Center. The decoder plugin is the one that allows Media Center to play and tag Wavpack files. The decoder plugin uses the open-source Wavpack library to do the dirty work.
It works for me. May not work for you. No warranty is implied. See the GNU public license.
If you select the "Use Correction Files For Hybrid Playback" option, then if a *.wvc file exists, the plugin will use the file for Lossless playback on hybrid encoded files.