I'm not sure about the specifics of your phone, hopefully it supports this.

If the music is in an unprotected format (such as mp3) you might be able to drag and drop music files from the iTunes library (not within the iTunes program, though) to the mp3 player/phone. If they are protected iTunes store purchases, you'll need to burn those to audio cd then rip them onto your computer. Make sure your preferences for importing are set to mp3 (in iTunes go to edit menu, then preferences, then advanced, then import using mp3 encoder). Then you'll need to locate the mp3 file in your library to drag and drop. If they are iTunes plus tracks you can convert them to mp3 within iTunes. Your importing preferences are set to mp3. In iTunes, right click on the song, then select convert to mp3. You still keep the original AAC version and you have an mp3 version as well. Again, find the file within your library and drag and drop.