Enc_Wavpack is the encoder plugin, which is used to rip and convert files into the Wavpack format.
It works for me. May not work for you. No warranty is implied. See the GNU public license.
You can select either lossless or hybrid compression. With hybrid, you can select whether or not to create *.wvc companion files for lossless playback. You can also select the target bitrate for the main file.
With either compression scheme, you can select the "Extra" processing level 0 through 6 (the default is 1) and compression level Normal, Fast, High, or Very High. Normal is the default.