send a single variable to a vbulletin default template

[White_Snake]

on cellarius article on vbulletin templating, he explains the way to send variables to preexisiting templates is this:

PHP Code:

$templater = vB_Template::create('mytemplate');
    $templater->register('my_var', $my_var);
    $templater->register('my_array', $my_array);
$templatevalues['my_insertvar'] = $templater->render();
vB_Template::preRegister('FORUMHOME', $templatevalues); 


but what when you need to only send a single variable to a existing template without the need to create a new template such as is requested on the first line?

i want to send a variable to the template editpost but this method doesnt seem to work, anybody can help me? thanks