First thing is change your existing stylesheet to media="all" so that your styling is copied over:
Code:
<link type="text/css" rel="stylesheet" href="css/00000001/cssui.css" media="screen">
becomes
Code:
<link type="text/css" rel="stylesheet" href="css/00000001/cssui.css" media="all">
Then you can create another stylesheet for print
Code:
<link type="text/css" rel="stylesheet" href="css/00000001/cssui_print.css" media="print">
And hide the left navigation, expand the main content area.
Code:
#wrapper-page { float: none; width: auto; }
#wrapper-index .sub-nav { display: none; }
That should solve 90% of the printing problems.