XML :: Flex Sorting Of ListCollection Sub Elements

In a Flex webapp, is there an easy way to go about applying a sort to the children of an XML element, based on the children's attributes? Example follows below:

XMLListCollection:
<a anotherProp="ABCDE">
<e prop="AB">1</element>
<e prop="BC">2</element>
</a><a anotherProp="FGEH">
<e prop="HF">3</element>
<e prop="AD">4</element>
<e prop="AC">5</element></a>

I would like to sort the <e> elements, within each <a> element separately, according to their "prop" attribute. My code for generating the array containing the <a> elements is along the lines of:
for each(var node:XML in initialInput:XMLListCollection){
if(node.localName()=="a"){
//I was hoping to be able to sort the <e> children of the node variable here
xmlListCollectionVar.addItem(node);
}}

At the end I would like the <a>'s to remain in their defined order, but their <e> children to be sorted based on the "prop" attribute. So far if I try:
node.children().sort=someSortVar
Where someSortVar has its fields set to:
SortFields("e.@prop",...)
I get an exception about a null value. Any way to convert the children list to XMLListCollection, sort it and integrate it back into the node variable?