Mine

function wp_cube_media_button($context) {
	$wp_cube_media_button_image = WP_CUBE_URL.'/images/wp_cube_media_button.gif'; 
	$wp_cube_media_button = ' %s'.'<a href="media-upload.php?type=wp_cube&amp;TB_iframe=true" class="thickbox" '."title='".__('Add a 360 view', $wp_cube_textdomain)."'>
  <img src='".$wp_cube_media_button_image."' alt='".__('Add a 360 view', $wp_cube_textdomain)."' /></a>";
	return sprintf($context, $wp_cube_media_button);
}
add_filter('media_buttons_context', 'wp_cube_media_button');