Example from sidebar.php:
<div class="sidebar-box border-radius-6px">
<h2>Dream Categories</h2>
<ul>
<?php wp_list_categories('title_li='); ?>
</ul>
</div><!-- Sidebar Box End -->
Lets say you want to display this only on a page called "about-us". use is_page() function provided by wordpress.
<?php if(is_page('about-us')) { ?>
<div class="sidebar-box border-radius-6px">
<h2>Dream Categories</h2>
<ul>
<?php wp_list_categories('title_li='); ?>
</ul>
</div><!-- Sidebar Box End -->
<?php } ?>
And as for the user level:
<?php if(current_user_can('level_10')) { // Level 10 = Administrator ?>
<div class="sidebar-box border-radius-6px">
<h2>Dream Categories</h2>
<ul>
<?php wp_list_categories('title_li='); ?>
</ul>
</div><!-- Sidebar Box End -->
<?php } ?>
Please see Wordpress User Levels
PS: I saw the plugin provided by aendrew and I had a look at it.
Try this:
Make a backup of widget_login.php file then open it, search for line 75 and replace it with update_option("widget_logic", "is_page('" . $wl_options . "')"); This should easy up the stuff a little, when you limit a widget you have to add is_page('bla-bla') in that input that line should only require bla-bla (If the page is called Bla Bla) [not tested, but you can give it a try.]