this is a kinda roundabout way, but i know no alternative:

if you know your friend's IP address, add it manually in the 'connections' tab.

you are then going to be directly connected to that host.

search for a file that you know your friend has, and in the results somewhere will be your friend's IP (sort by 'host' to make it easier).

right click on that host and choose chat or browse host.

also: make sure he doesn't have 'allow chat' disabled.

hope that helps, good luck!