So, you have a VCD disc and you want to have one song (not the video, but only the audio) from the VCD in separate audio file, right?
Copy the DATs to your HDD, go to TMPGEnc's MPEG Tools, cut the song you want and save it as a separate MPEG-1 file. Then go to MPEG Tools again, open the MPEG-1 and use Demux and it will demux the file into separate video (.m1v) and audio (.mp2) files.