Showing private posts in results

Hi everyone I am trying to modify WP to fit the needs below:

What we want is to do is have users come to the site and see the posts listed by categories. So far so good.

The information from each post we want everyone (not logged in) to see from each post will be posted before the “READ MORE” line (including instructions on how to create an account and request access to the post).

After the users create the account and meet the criteria to see the full post we will use “Disclose-Secret” plugin to offer the specific users access to the specific post they requested. (this plugin permits us to give access to logged in users to specific posts, it works just as we want)

What happens is that posts marked as PRIVATE are just not being displayed anywhere in the site until the users login (by design of WP).

Well I want to break that and show the private posts to everyone up until the “READ MORE” and still show a 404 (modified) when someone tries to view the full post page by clicking the “READ MORE”.

In other words, how can I make WP display PRIVATE posts on the category/archive/search results lists but not show the actual post page?

Can someone point me to the code in WP that filters the PRIVATE posts out from the category/archives/search results? I want to delete/modify that code.