An old question, but an answer may help others when searching.
Get a MicroSD card which is compatible to your MP3 player device. Then insert that MicroSD card in another device from where you want to copy the files, (like your mobile phone).
Now your MicroSD card hast the mp3 files that you need.
Just put the MicroSD card in your MP3 player and away you go.
Regards,
Peter.
