asterisk users - Apr 2007 - Asterisk, nat, gizmo and fwd

Hi there everyone!

I use asterisk as a home pbx. My internet connection is a DSL one,  
and I have a Linksys WRT54G that nat things for me in a 192.168.X.X  
style network.

I've installed asterisk on my mac, and tried several examples I've  
found on the net (voip-info, gizmo, etc.) about how to create a Gizmo  
and a FWD trunk. However, all my attempts failed. The FWD thing kinda  
worked, but it wouldn't receive any calls. The Gizmo one worked ONLY  
to call their echo test - If I tried to call a real number I got some  
serious noise, sometimes the phone ringing, but never getting audio  
through. It also brings my asterisk down (1.4.0) - it just hangs,  
without the peers managing to authenticate on the server again.

Has anyone succesfully managed to connect to Gizmo and FWD in a  
similar setup and would be so kind to share the configs?

[]'s

Francis