Chrisago on "Display specific category items."

Hi all,

Any suggestions on how to display specific category items from the portfolio?
Instead of 4 random items from the whole portfolio I would like to post 4 related portfolio items with the main portfolio item the user views.

Something like 4 "related products" with the main product.

The code excludes 3 items which don't want to show and displays all portfolio items:

// Create a new WP_Query() object
$wpcust = new WP_Query(
array(
'post_type' => array('portfolio'),
'post__not_in' => array(1366, 1359, 1353),
'orderby' => 'rand',
'showposts' => '4' )
);

Any help is really appreciated!