I'm not using lighttpd. But if you could experiment with it and report, it would be a valuable enhancement to the usability of LXR.
I just had a look to the lighttpd official site. There is an extensive configuration section in http://redmine.lighttpd.net/wiki/lighttpd where you should find everything you need and more.
Once everything works fine, if you feel brave, please write a small guide or howto I'll add to the website and the manual.
To contact me while you experiment, use ajlittoz (at) users (dot) sf (dot) net so that the mailing list is not cluttered with interim details.