Requires YAJL to build, and this doesn't include the necessary
automake changes. Can be built using
./configure CFLAGS="-I/usr/include/yajl" LIBS="-lyajl" --enable-soundcloud

Add the following to your config:

playlist_plugin {
        name "soundcloud"
        enabled "true"
        apikey "c4c979fd6f241b5b30431d722af212e8"
}

Then you can stream from soundcloud using calls like:

mpc load soundcloud://track/<track-id>
mpc load soundcloud://playlist/<playlist-id>
mpc load soundcloud://url/http://soundcloud.com/some/track/or/playlist

For the last case, you can leave off the http:// or
http://soundcloud.com/ .