you can use the jpeg hack/use
ICHWM
This will basically rename your file as a picture which you can send wirelessly, but you need to connect it to your computer to turn the file back into an mp3.
Alternatively, if you have done the HDD hack, if you look in the root directory under storage, near the bottom will be a file with the name of the person who sent you the file. If you delete that file you should be able to receive the song again.