If you want Lucee to use the .htm and .html file extensions instead of (or in addition to) .cfm and .cfml you can set this up in 3 quick steps.
1. Stop Lucee
2. Edit the web.xml file located at
/conf/web.xml
From:
CFMLServlet *.cfc *.cfm *.cfml /index.cfc/* /index.cfm/* /index.cfml/*
To:
CFMLServlet *.cfc *.cfm *.cfml *.htm *.html /index.cfc/* /index.cfm/* /index.cfml/*
3. Start Lucee