darkplayer javascript, shuffle through a few songs Options

[silence]

how do you modify the darkplayer code so that it shuffles through only a few songs on your playlist and not the whole playlist?

if (shuffle == 1) {
var randsg = Math.floor(Math.random()*songs.length);
document.darkplayer.FileName = songs[randsg];
document.darkplayer.scr = songs[randsg];
document.forms['form'].playlist.options[randsg].selected = true;

wat do you do to the second line to make it random for only a few songs?
declare something new? i hope someone knows what i'm talking about.