If you use the AutoDJ make sure it is set to public, you can find this under "Mount Points" in the settings. Also make sure the Overrides has "Advertise in directory" set to "Always" or "Determinated by source".
The last step is to make sure that under Advanced "Directory listings URL" is set to yp.shoutcast.com
Then just restart/reload your server and you're done. Make sure you use a common genre, if not SHOUTcast.com will reject your listing.