You basically create a new array in that function, populate it, then return the readied array. Like this:
function getScoreArray():Array {
var a:Array=[];
for each(var i in myScoreArray){
a.push[i];
}
return a;
}
In fact, this can be done with more ease using Array:slice()
function.
function getScoreArray():Array { return myScoreArray.slice(); }