This is mentioned in the iTunes/iPod Sticky in the Open Discussion section. There's also a sample image on page 2 about manual updating. The iPod tutorial at the apple site will show you how to do it. Look near the bottom of this post at 'Manually Manage Songs & Playlists.'
http://www.gnutellaforums.com/showth...776#post129776 This simply points more directly where to find it.