[totaltec]

Have you tried my suggestion above?

I'll explain it again.

Create a static page containing:

{if $login eq ''}
Yes you have to register. Go here: <a href="register.php?custom=yes">Register</a>
{else}
You are registered and logged in! Congratulations!
{/if}

Make sure you have "parse smarty tags" enabled. Take note of the pageid of the custom page.

Now look in include/register.php
Find this line:

$script = 'address_book.php';

Change it to:

if ($custom == 'yes') {
  $script = 'pages.php?pageid=7';
}else{
  $script = 'address_book.php';
}

Change the pageid to your custom page's id.

Works on my test site here: http://trainingpen.com/Special.html