Custom ids for <li> in widgetized sidebar?

I created a custom theme for the company I work for. The sidebar did not have to be “widgetized” or widgets “compatible” until now. I´m required to use a couple of widgets. I know how to widgetize the sidebar:

Included the usual snippet:

<?php 	/* Widgetized sidebar, if you have the plugin installed. */
if ( !function_exists('dynamic_sidebar') || !dynamic_sidebar() ) : ?>

into sidebar.php and this code in the functions.php:

<?php
if ( function_exists('register_sidebar') )
	register_sidebar(array(
		'before_widget' => '<li id="%1$s" class="widget %2$s">',
		'after_widget' => '</li>',
		'before_title' => '<h2>',
		'after_title' => '</h2>',
	));
?>

The sidebar is widgetized but the problem now is that all my carefully created ids for the different
<li> are gone (some
<li> elements require different styles and since the blog has to work with IE6 and e.g. child selectors are not supported by IE, I need this IDs to reference the different elements).
I could try to rewrite my css again, but isn´t there a way to widgetize the sidebar without wordpress using this non-semantic ids?

Thank you!!