You can use ArrayCollection and SortField to sort a list of items based on one or more fields:

this.names= new ArrayCollection();
names.addItem({first:"John",last:"Travolta"});
names.addItem({first:"Miguel",last:"Nunes"});
    names.addItem({first:"Christina",last:"Aguilera"});
names.addItem({first:"Michael",last:"Jackson"});
var sort:Sort= new Sort();
sort.fields=[new SortField("last",true,true), new SortField("first",true,true)];
names.sort=sort;
names.refresh();

You can try the adobe flex example here. View source is enabled.