Which part - do you mean the Webmin front-end onto configuring the Apache web server? I think that since all Webmin is doing is writing to the various Apache config files, it should work OK if LSWS is under the hood and configured to pretend to be Apache.
But there is no Webmin module specifically for LSWS, if that's what you mean. There would be no point, since LSWS has its own web front-end.
Otherwise, Webmin itself runs under its own webserver. It has no dependency issues with LSWS or any other web servers.