Find tag which contains some text you're looking for using jQuery. It's a common task if you want to modify some elements on page but you can't modify html-code of page.

		<tr>
		<td nowrap="true" valign="top" width="190px" class="ms-formlabel"><h3 class="ms-standardheader">
		<nobr>City</nobr>
		<div>
			<!-- Image -->
			
			<!-- /Image -->
		</div>
	</h3></td>
		<td valign="top" class="ms-formbody">
		<!-- FieldName="City"
			 FieldInternalName="City"
			 FieldType="SPFieldText"
		  -->
			<span dir="none">
		<input name="ctl00$m$g_b9ee4111_$ctl00$CustomFieldIterator1$TextField" type="text" maxlength="255" id="ctl00_m_g__TextField" title="City" class="ms-long ms-spellcheck-true" /><br />
	</span>
			
			
		</td>
	</tr>

<script>
$("tr td h3:contains('City')").css( "text-decoration", "underline" );
</script>