Mac os X Client sshd

Hello, I would like to run the built-in ssh server of mac os x client, i.e. the one you turn on in the sharing pane of system preferences, but on port 80 instead of 22. I have tried modifying the /etc/sshd_config file putting 80 instead of 22 in the port option, but that has had no effect at all.... Could you tell me what I am doing wrong? thanks