I've read in http://redmine.lighttpd.net/projects/1/wiki/Docs:ModProxyCore that sticky sessions are not currently implemented in lighttpd. I'd like to know if it is possible to have sticky sessions using lighttpd as a loadbalancer. Perhaps implementing the sticky sessions using fastcgi or applying some patch?
Do you really need to use Lighttpd as your load balancer? You might be better off using something like HAproxy that supports source address hashing