How to make simple banner rotation?

[FractalizeR]

In VBulletin3 I did something like this:

global_start plugin:

PHP Code:

$fr_bannerId = mt_rand(1,6);
$fr_bannerURL = "http://www.gsmforum.ru/images/ownpictures/". $fr_bannerId .'.swf'; 


ad_header_logo template

<object width="500" height="90">
<param name="movie" value="$fr_bannerURL">
<embed src="$fr_bannerURL" width="500" height="90">
</embed>
</object>

But in VB4 it no longer works, of course. Moreover,

class_bootstrap.php, Line 289

PHP Code:

// advertising location setup
$ad_location['ad_header_logo'] = vB_Template::create('ad_header_logo')->render(); 


It seems, now the contents of advertisement templates can't be dynamically generated because template is rendered automatically and there is no way to insert vB_Template::register() call.

Can someone suggest an easy way to have simple banner rotation inside advertisement templates like I did in VB3, but in VB4?