If its in .mp3 format you can use an audio converter  to change it into a .wav file. Now, I used to have a link to a site where such programmes were available, cant find it right now but if you try a google search for 'mp3 to wav converter' you should be able to find something no problem. The programme I used in the past was called 'softdiv audio converter', if that helps. Once you have converted your mp3 into a wav file, its just a simple case of re-naming it to 'uimusic.wav' and using it to replace the file of that name in your music folder. Backup your original uimusic file first of course. That should do the trick. As a word of warning, it doesnt always work if the files kbps or khs varies a great deal from the original file, but you should be okay, fingers crossed.