problem with adding another rule with wp_rewrite

hello

i set my wordpress permlink to /%category%/%postname% now i’m using Nextgen Gallery so when i have a gallery in a page it will be something like /cat/page?gallery=10 i want to make it something like cat/page/gallery id/ i tried alot with wp_rewrite … but no luck … any help ?

this is what i’m testing on .. it’s not my code it’s provided from wordpress … i will put everything in its place when i found the way … so don’t worry i will not flushRules on init … thanks a lot

add_filter('rewrite_rules_array','wp_insertMyRewriteRules');
add_filter('query_vars','wp_insertMyRewriteQueryVars');
add_filter('init','flushRules');

// Remember to flush_rules() when adding rules
function flushRules(){
    global $wp_rewrite;
    $wp_rewrite->flush_rules();
}

// Adding a new rule
function wp_insertMyRewriteRules($rules)
{
    $newrules = array();

    //i don't know what should i put here
    $newrules[''] = '';
    return $newrules + $rules;
    //
}

// Adding the id var so that WP recognizes it
function wp_insertMyRewriteQueryVars($vars)
{
    array_push($vars, 'id');
    return $vars;
}