1) Go to your favorite station aggregator (like shoutcast.com)
2) Right click on the tune-in and copy the link (it should end in .pls)
3) Paste the link someplace you can see it
4) Add a new station to CastCatcher and type in the link
5) Hit save and you’re done!
Update: Unfortunately, shoutcast.com has changed the way their station links work so we will release a new version of CastCatcher to Apple later tonight to handle this change. Other shoutcast streams will still work with CastCatcher (we simply need to change the check for .pls in the name). Also, a request for m3u was submitted — we evaluate the amount of effort to get this into v1.2 and welcome more user suggestions!
Update 2: For the first reviewer trying to add WNYC-AM, look at the link on their website (left side, next to “MP3″) called “32k.” When you mouse over it you’ll see a link such as “http://www.wnyc.org/stream/am.pls” — you can add that to CastCatcher directly. 
Update 3: Workaround for Shoutcast.com streams until new version is approved — Simply click the station name link on the shoutcast.com page (Station: NameLinkIsHere) and go to the station’s website. From there, find the link for their winamp/shoutcast/mp3 stream (again, it ends in .pls) and add that to CastCatcher.