this is a copy direct from the "navbar" usercp link..
Code:
<td class="vbmenu_control"><a href="usercp.php$session[sessionurl_q]">$vbphrase[user_cp]</a></td>
But if the users are logged in just link to
Code:
http://www.yourforum.net/yourforum/usercp.php
and they will reach their own cp, no reason to make it defficult

if they are not logged in, a login box is usually appearing.. test it out..