Sorry to chum in :)
var re:RegExp = /(("|').*(?=\2)\2)|(\s[^\s"]+(?!\s"))/g;
var text:String = <![CDATA[Lacrimosa dies illa,
qua resurget ex favilla
iudicandus "homo reus".
Huic ergo parce, Deus:
Pie "Iesu Domine",
dona eis requiem.]]>.toString();
var result:Object;
while (result = re.exec(text))
{
trace(result[0]);
}

