I'm using Category Access plugin which keeps all posts private unless the user is logged in. (guests have no post view privelages)
If user isn't logged in (counted as guest) they get the sidebar only and a message in a post box telling them they need to log in to view posts with a link to the login.
This works fine but...
Permalinks are resulting in a browser default 404 error (with no parts of the site visible) to any user that isn't already logged in.
If the user IS logged in they can go straight to the post as normal.
The private target audience is as techically savy as a bunch of cavemen and won't know to go login first when met with a blank page.
I need to have the 404 redirect to the login page instead and upon succesful sign-in, forward them to the permalink.
How do I do this?