OK, so I went home, and worked on this some more...
Here's the current structure :

PAGENAME=>  {description    =>$desc,
             traverse_list  =>{pagename_1  =>  1,
                               pagename_2  =>  0,
                               ...},
             traverse_sub   =>\&sub,
             validator      =>\&sub,
             errorhandler   =>\&sub,
             template       =>$filepath,
             postsubmit     =>\&sub,
             params         =>[$param1, $param2...]}
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description is a plain string used as an identifier for the page. It currently provides data for the template's <TITLE> tag. This is probably not so hot.

traverse_list is an anonymous hash which stores which pages the current page could link to. The key should be a PAGENAME, and the value of the key determines if the postsubmit subroutine should be called when moving to that page.

traverse_sub is a sub ref which determines which page should be displayed next. It returns a string, which should match one of the keys in traverse_list. It is passed 2 variables, $vars and $errorcode. $vars is a hash ref used to populate the template. $errorcode is generated by the page's errorhandler.

validator is a sub ref used to validate data or business rules. I envision it as returning an integer code, or a bitmap.

errorhandler is a sub ref. It's little experimental -- I picture it being called if postsubmit fails horribly. I was planning to eval postsubmit and call errorhandler if it died, but I'm thinking of expanding its scope. *shrug*

template is a string containing the path to this page's TT2 encoded HTML template.

postsubmit is a reference to a subroutine called after validation. Like traverse_sub, it's passed $vars and $errorcode. If you need to hit a DB, or process user input in some fashion, this is place to do it.

params defines a list of html parameters which will "be sticky" (is that the right term), and be passed as hidden HTML input fields.

In my CST, I will polish the engine and post it. I appreciate the replies and /msgs I've gotten so far, and am trying to incorporate them into the changes I'm making; please let me know if you've got more.