Hi Hugo,
I believe that this is the script that gets added as S91lighttpd: https://github.com/seL4/sel4webserver/blob/master/lighttpd/lighttpd.sh
If you want more details of how lighttpd is built and overlayed you can check the cmake file: https://github.com/seL4/sel4webserver/blob/master/lighttpd/Findlighttpd.cmak...
Regards, Olof