Simply load the module after loading highlight.js. You'll use the minified version found in the dist directory. This module is just a CDN build of the language, so it will register itself as the Javascript is loaded.

<script type="text/javascript" src="/path/to/highlight.min.js"></script>
<script type="text/javascript" src="/path/to/sfz.min.js"></script>
<script type="text/javascript">
  hljs.highlightAll();
</script>

sfz language grammar for highlight.js is released under the BSD-2-Clause License. See LICENSE file for details.