For the example you mentioned, you can add a filter to the stylesheet_directory
hook
add_filter('stylesheet_directory','change_stylesheet_dir') ;
function change_stylesheet_dir($stylesheet_dir, $stylesheet, $theme_root) {
# do stuff - change the stylesheet directory
$new_stylesheet_directory = 'http://mysites.com/hello/';
return new_stylesheet_directory ;
}
For any of the other parameters for bloginfo, you can look at the code for for bloginfo
, which is in wp-includes/general-template.php. Follow the calls made for other bloginfo parameters to see whether there is a filter for it.