[Andreas]

You can't change data in Hidden fields they are hidden...

Of course you can (even if it mens having to save the HTML, editing the contents and then submitting the form). Every user input can be changed/faked - always keep that in mind!

Adding a filed to tabel session is simple:
1) ALTER the table
2) To set it:

PHP Code:

$vbulletin->session->db_fields['foo'] = TYPE_STR;
$vbulletin->session->set('foo', 'bar'); 


That's it. The value will be read automatically and is available as $vbulletin->session->vars['foo'] in the next script call.