Here’s an example:
m4b-tool merge "Just Listen" --jobs=10 --output-fi
le="Just Listen.m4b" --name="Just Listen" --album="Just Listen" --artist="M
ark Goulston" --use-filenames-as-chapters
where “Just Listen” after merge is the folder containing the WAV, MP3 etc files. If “cover.jpg” is in that folder, it will be embedded in the final M4B file.
To add chapter information stored in file “chapters.txt” to an existing file, without recoding, use --no-conversion
m4b-tool can be found at https://github.com/sandreas/m4b-tool
Krtekz's Random Notes 