I'm not sure that I understand your question! Youâ€™ve got a bunch of MP3 files, right? If it is so, you could just choose the â€œaudio profileâ€ in Nero and then drag/browse the files into the appropriate window and burn them.
You could also rip the audio tracks from your DVD with â€œDVD Audio Extractorâ€ and then burn them with Nero. This way you can ensure to get the best possible quality.