use xajax

I do not know well smarty but smarty can use xajax in its temp engine
(...from xajax..org
xajax can be used with the Smarty templating system by creating a variable in smarty that contains the xajax javascript:
$smarty->assign('xajax_javascript', $xajax->getJavascript());
Then you can use {$xajax_javascript}in your header template to use xajax on your site.

)