simply make a link using the xml to that part of the admincp, for example
PHP Code:
<?xml version="1.0" encoding="ISO-8859-1"?>
<navgroups product="Icash">
<navgroup text="ICash Settings">
<navoption displayorder="1">
<text>Main Settings</text>
<link>options.php?dogroup=icash&sdo=options</link>
</navoption>
<navoption displayorder="2">
<text>Donate To Members</text>
<link>icashadmin.php?act=donate_to_all</link>
</navoption>
</navgroup>
</navgroups>
i took that from my ICASH hack.