Rewrite URL for results of a custom WP_Query

You could try using the add_rewrite_endpoint function, which would actually let you avoid any htaccess modification (unless you need $_GET).

Example:

function add_custom_rewrite_ep() {
    add_rewrite_endpoint('cata', EP_PAGES);
    add_rewrite_endpoint('catb', EP_PAGES);
    add_rewrite_endpoint('catc', EP_PAGES);
}
add_action( 'init', 'add_custom_rewrite_ep' );

Make sure you flush your rewrite rules.

So then, if your URL is /questions/cata/foo/catb/bar/catc/more/, you can access the values with get_query_var like so:

$x = get_query_var('cata','default'); // equals 'foo'
$y = get_query_var('catb','default'); // equals 'bar'
$z = get_query_var('catc','default'); // equals 'more'

It is difficult though to give you an exact solution without knowing how your url’s are generated, if you’re using the $_GET global, and how you’re using the values in your code.