__callStatic method handler passed to add_action causes bug in PHP <5.3

I have a class that handles AJAX requests for my plugin. The class has a __callStatic wrapper for all actions, which subsequently calls non-static methods for each action, like so:

class TP_AJAX_wrapper {

 public static function __callStatic( $name, $args = null ) {
  check_ajax_referer( 'tp_ajax_nonce' );

  $out = array();

  try {
   $res = call_user_func( array( __CLASS__, $name ) );
  } catch(Exception $e) {
   $out['error'] = $e->getMessage();
  }

  $out['responseStatus'] = $res ? 'ok' : 'null';
  $out['response'] = $res;

  echo json_encode($out);

  die();
 }

 protected static function someAction() {
  return array( 'someValue' => 3 );
 }
}

Then I have an array of actions which I initialize using:

foreach ( $ajax_actions as $action ) {
    add_action ( 'wp_ajax_tp_'.$action, array( 'TP_AJAX_wrapper', $action ) );
}

This works great for PHP 5.3+, but fails miserably on older versions.

Warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, ‘TP_AJAX_wrapper::someAction’ was given in /path/to/wordpress/wp-includes/plugin.php on line 395

Since it’s written in a plugin, used on all sorts of hosts, some of which support PHP 5.3, others which don’t, I have to make it a little more flexible. What I can’t figure out is a way to emulate __callStatic (introduced in 5.3) for older versions of PHP.

What I’m looking for is a way to emulate the __callStatic wrapper for older versions. I’ve tried using __call as well, which is supposed to handle static method calls if the first argument is a classname, rather than an object, but I keep getting the same error.

Halp?