Conditionally Enqueue Script for IE browsers less than IE 9

This code snippet will conditionally enqueue script for ie browsers LT IE9. Put this in your functions.php file.

/**
 * Conditionally Enqueue Script for IE browsers less than IE 9
 *
 * @link http://php.net/manual/en/function.version-compare.php
 * @uses wp_check_browser_version()
 */
function wps_enqueue_lt_ie9() {
    global $is_IE;
 
    // Return early, if not IE
    if ( ! $is_IE ) return;
 
    // Include the file, if needed
    if ( ! function_exists( 'wp_check_browser_version' ) )
        include_once( ABSPATH . 'wp-admin/includes/dashboard.php' );
 
    // IE version conditional enqueue
    $response = wp_check_browser_version();
    if ( 0 > version_compare( intval( $response['version'] ) , 9 ) )
        wp_enqueue_script( 'wps-html5shiv', 'http://html5shim.googlecode.com/svn/trunk/html5.js', array(), 'pre3.6', false );
}
add_action( 'wp_enqueue_scripts', 'wps_enqueue_lt_ie9' );

Source