It took a bit, but I finally found how to get the Internet radio applet to do what it would seem it was meant to do. Hope this helps someone.

1. Surf to shoutcast.com, or another stream aggregator, on your 770.

2. At shoutcast.com, click 'Tune In' next to the station you want to stream. The 'Audio Player' application should automatically launch, and begin playing your station.

3. You'll note that most stations will display in Audio Player as multiple streams. (I believe each listing represents a different server, and the numbers indicated in parenthesis represent the number of active and total possible streams of each host.) Single click on any one server that is not maxed out to select it.

4. From the Audio Player menu, select Track > Add to favorites. This adds the stream (and not the .pls file that you may have previously tried to manually enter into Audio Player) to the list available from the Internet radio applet.

5. From the Audio Player menu, select Playlist > Open...

6. Open the file titled 'favourites' that the file manager automatically directs you to. (For those who prefer to work under the hood, the favorites list is actually stored in the file /home/user/MyDocs/.sounds, and can be edited there.)

7. Your favorites list will display in Audio Player.

8. Hold the stylus down on the name of the station you'd like to rename, and name it as you'd prefer.

Enjoy!