I use the program Psi v 0.9.3 found @ http://psi.affinix.com
You wll have to find one that has a google talk connection. The one above doesen't. And I thought this whole time I was using it. Sorry for misleading you.
But what is so strange, when I add a contact, I do not have a "google" account that I may add. So I us "jabber" as the transport, put in my friends google email address and it adds it, no prob.
I'm using Adium 0.8.6 it that helps. But adding a user via jabber, it works. Here's how I added them:
friendsname%google.com@jabber.3gnt.org
and he appeared in my list. If he signs on, I can talk to him. But it's been a while since he's logged on.
Well, hope this helps. If not... I have no idea what else to say that might assist you.