If abcde doesn't do what you're looking for, you'll find a discussion of transcoding MP3 to OGG here (http://www.vorbis.com/faq/#transcode), including a link to some transcoders. Be aware of the dependencies for those scripts. In fact, abcde is itself just a script, and installing it may or may not have installed the actual executables it relies on (e.g. oggenc).