No and there won't be.

is there any particular reason why?

Playlist are loaded and stored on the server and could be abused if non-admins can edit them. Playlist need to be Serverside in order to allow synchronisation between clients, without compromising on security.

When the server allows custom urls (it is by default, otherweise the radio will reject them), you can write up an wiremod e2. It would contain a list and the radio has wire ports to control the radio and the e2.

Otherwise ask an admin on your server to extend the radio playlists to your wishes.

hm i guess, i just don't really see how allowing people to use m3u playlists would be a bad thing but of course it's not my addon
thanks for the suggestion about the e2 though, i'll try that out

When everyone can edit the files, there would be vandalism and also malicious urls inside them. The playlist are accessible from every radio entity owned by anyone on the server.