Two ideas that come to mind are to try a Direct Connect with them. And the other is to search for any files you know they have & then if you see their id in the search results you can Chat with them. It's not always easy browsing or direct connecting & helps if you both have chat enabled & for DC if you both have available upld & downld bandwidth & slots. And not being impaired by improperly setup firewalls. More hints:
How to Direct Connect, Browse & Chat