create a hidden form element to capture the label, and use javascript to change the hidden form elements value when the select list is changed.
Here is an example:
<input type="text" name="hiddenLabel" id="hiddenLabel" />
<select name="selectValue" id="selectValue" onChange="document.form1.hiddenLabel.value = document.form1.selectValue[document.form1.selectValue.selectedIndex].text">
<option value="make a selection"></option>
<option value="1">one</option>
<option value="2">two</option>
<option value="3">three</option>
<option value="4">four</option>
<option value="5">five</option>
</select>