Double NAT issues?

[CuriosityBlue]

I really really want this to work, but I am having timeout issues when trying to connect to the server through the special URL I created. I suspect I'm having double NAT issues, as I can't think of any other reason I'm failing. My ISP provides service in this way, and they have given me an outside static address that forwards through so I can SSH/FTP in to my network. I'm wondering if there is a place where I can define this address so I can connect straight to the Subsonic server from outside my own network (like from work) without getting lost in translation.

Anyone know if this is possible? Thanks in advance.

I love the pretty orange submarine, by the way.

MacOS 10.6.3
Airport Extreme with default port 4040 forwarded.