If you click on the home button.. then bottom right it says logout.. when you log out and come back to the board you see a login area for username and password.
find that form in the templates and just copy it to wherever you want.. and I would say.. just include the global.php file and you should be set..
find out what the if ($submit) value is.. too and get that part of the script. or have it redirect to the original...
---- update
if you like the look of geeknews.. and it is phpnuke.. take a peak at
www.phpportals.com ..
and the middle top part about reviews and articles.. I am going to work on.. to add as an addon eventually when I get the time.