<li id="menuitem_4_private" class="mainlevel_active_private"><a id="menulink_4_private" class="mainlevel_active_private" href="#">Portfolio</a>
<ul id="menulist_4_private" style="visibility: hidden; top: 87px;">
<li id="menuitem_4_1_private" class="sublevel_private">
<a id="menulink_4_1_private" class="sublevel_private" href="#">Testimonials</a></li>
<li id="menuitem_4_2_private" class="sublevel_current_private">
<a id="menulink_4_2_private" class="sublevel_current_private" href="#">Case Studies</a></li><li id="menuitem_4_3_private" class="sublevel_private"><a id="menulink_4_3_private" class="sublevel_private" href="#">Gallery</a></li>

This is a section of my menu and I wish to target the <ul> below "mainlevel_active_private" depending on which menu item is active tried various things such as mootools etc. My menu is rendered in Joomla and makes use of "easymenu" - any suggestions or if you need more info let me know.