Burn the track(s) to a compact disc and make sure that you burn an audio CD and not a data CD.
Right click the media file and select 'Convert Selection to MP3'.
Use the iTunes to access the audio CD and add the media files to the library.
If you've a large number of media files to be converted to MP3 format then you may even use a CD Emulator to simulate a real CD burner to avoid the multiple CD-R discs.
clipped from: www.tech-faq.com