omegatron - PostNuke only uses cookies to store the session id, the user authenication then uses that session id internally to tell if the user is logged in or not. I think it's a simple change to skip the cookie-based username/password that PP uses.
PostNuke has a few API routines to check if the user is logged in/out and to retrieve the user name/id. Shouldn't take to long to adapt the
postnuke.php file to use those.
Also will have to adjust the CSS files cause it basically overwrites the equivalent styles (e.g. links) that PostNuke uses.
continuing on .............