here's the config from the Map Lab server
You can do as DJ suggests and make a tv config, or you can just add this text to your server.cfg file, at the top, after the server name bit
tv_enable 1
tv_port 27117
tv_delay 120
tv_name "LnC|PlaygroundTV"
tv_title "LnC|PlaygroundTV"
tv_allow_camera_man 0
tv_transmitall 0
tv_relayvoice 0
tv_autorecord 1
tv_delay is the delay between the server and the tv viewer, in seconds
tv_allow_cameraman can be set to 1 to allow source tv viewers to be cameramen and have the other viewers select their view/.
tv_transmitall can be set to 1 to enable every player angle to be broadcast - useful on gamedays but not for general use as adds more burden
tv_relayvoice - keep this off at 0, or in game chat will lag the feed for viewers
tv_autorecord - you have a choice. If you have desktop, console access to your server you can just manually reocrd demo's ad-hoc. If you want all activity on the server recorded, set to 1 and make sure you clean out your recordings regularly cos they soon get HUGE.
hope that helps.