Can't figure out how to receive http requests using lighttpd

I have a simple lighttpd web server running off my router. In it's .conf file I know I need to set

$HTTP["querystring"] =~ "cams=on" { telnet to turn on cams via managed poe switch }

The issue I am having is trying to figure out how to actually get it to run a script that sends telnet commands to my poe switch. I've never done anything like this and I'm unable to find any help for anyone not angry familiar with web serving.