[wp-hackers] Custom Permalinks - how to?

[Niels Hackius]

Fellow Wordpress-Hackers,
I asked this in the forums (http://wordpress.org/support/topic/75123),
but I didn't get an answer:
I am working on a plugin for the singapore-image-gallery (sgal.org).
What I would like to do is create permalinks that are calling a
certain page. Usually I create a page and singapore creates links like
this:
wordpress.com/index.php/foto/?gallery=test
The gallery is called test. The page title is "foto". Now I would like
it to look like this:
wordpress.com/index.php/gallery/test and point to the above URL.

Now I have a function like this:

        function singaporeRewriteRules($rules)
        {
                global $wp_rewrite;

                // add rewrite tokens
                $keytag_token = '%gallery%';
                //$rewrite->page_structure =
$rewrite->page_structure."/".$keytag_token;
                $wp_rewrite->add_rewrite_tag($keytag_token, '(.+)',
'page_id='.get_option('singapore_page').'&gallery=');

                $keywords_structure = $wp_rewrite->root
."gallery/$keytag_token";
                $keywords_rewrite =
$wp_rewrite->generate_rewrite_rule($keywords_structure);

                return ( $rules+$keywords_rewrite );
        }

        add_action('rewrite_rules_array',array($this,'singaporeRewriteRules'));

What it outputs in the rewrite-rule-Array is this:
[index.php/gallery/(.+)/?$] => index.php?page_id=67&gallery=$matches[1]

This obviously doesn't work. I also tried to create links like this:
* [index.php/fotos/gallery/(.+)/?$] => index.php?page_id=67&gallery=$matches[1]
* [index.php/(fotos)/gallery/(.+)/?$] =>
index.php?page_id=67&gallery=$matches[1]
* [index.php/fotos/gallery/?$] => index.php?gallery=$matches[1]

But it didn't work either, maybe someone could help me out, please?

Thank you very much,
Niels Hackius