[Hauts]

Навоял по-быстрому.

function formatToString(n, pattern:String) {
	// pattern like "## ### ### ###"
	var a:Array = n.toString().split("");
	var p:Array = pattern.split("");
	var resultString:String = "";
	var l:Number = pattern.length;
	for (var k:Number = 0; k<l; k++) {
		if (p[k] == "#") {
			resultString += a.shift().toString();
		} else {
			resultString += p[k];
		}
	}
	return resultString;
}
 
trace(formatToString((89139131313).toString(), "# ### ### ## ##"));
trace(formatToString("89139131313", "#-###-###-##-## (MTS)"));
trace(formatToString("0123456789", "# # # # # # # # # #"));