I'm sorry I can't offer any real assistance because FFMpeg and other 3rd party encoders are not our products, you should probably contact their authors or read the docs to get more detailed help.
If you use FFMp3g, the part required by RadioBOSS is marked in bold (please also note the last dash):
<path>\ffmpeg.exe -loglevel -8 -f s16le -ac {Channels} -ar {SampleRate} -i - -c:a alac -
The -f, -ac, -ar parameters configure input stream format, -i - and - at the end instruct it to read/write from stdin, -loglevel prevents any log messages in the stream. You should leave those as is. The -c:a part sets the codec. You probably need to also set the container for the stream, e.g. -f adts (however I'm not sure what container should be used for ALAC)