I needed to convert the customers 3-character input into lowercase-uppercase-lowercase (e.g. "eMc").

Monogram case with javascript

<div class="custom monogram">
	<label>ADD A MONOGRAM:</label>
	<input type="text" onkeyup="caseChange()" id="monogram" maxlength="3" />
	<p class="notes">Please enter your monogram here in the correct order: first, last, middle. Monogram may not be changed to another style or full name.</p>
</div> <!-- end .custom .monogram -->

<script>
	function caseChange() {
		var str = document.getElementById('monogram').value;
		var one = str.substring(0,1);
		var m1 = one.toLowerCase();
		if(str.length>1) {
			var two = str.substring(1,2);
			var m2 = two.toUpperCase();
		}
		if(str.length==3) {
			var thr = str.substring(2,3);		
			var m3 = thr.toLowerCase();
			document.getElementById('monogram').value = m1+m2+m3;
		}
		if(str.length==1) {document.getElementById('monogram').value = m1;}
		if(str.length==2) {document.getElementById('monogram').value = m1+m2;}
	}
</script>