Here’s another way to do it. This is off the top of my head and untested but I’m sure someone will correct me if I’m wrong.
The [[Personalize]] snippet will let you test whether a user is logged on. Create a yesChunk with nothing in it (or with your content in it if you want to be really secure) and a noChunk that redirects them to another page using sendRedirect(). You’ll need to create your own tiny snippet containing just the sendRedirect() call to put in your noChunk. IOW, the noChunk will contain just [[MyRedirectSnippet]] and you’ll create that snippet which will contain the following code:
<?php
sendRedirect([~docID~]);
?>
Replace docID with the document number of the page you want to send them to.
You can get the personalize snippet here:
http://modxcms.com/Personalize-2.0-871.html
The sendRedirect docs are here:
http://wiki.modxcms.com/index.php/API:sendRedirect
If you want to get a little fancier, you can put the docID as a parameter in the snippet call:
[[MyRedirectSnippet? &docID=`6`]]
(this will redirect them to document number 6.)
Then change the snippet code to (note the added dollar sign):
<?php
sendRedirect([~$docID~]);
?>
Bob