Method 3 in Tesserax's doco covers one method.
https://discussions.apple.com/community/wireless/airport?view=documents
See top article.. remote access.
I would do it a little differently.
Since the TC should really be in bridge there is no need for most of the setup as Tesserax does it.
Your main router is the Comcast.
See the instructions for port forwarding.. eg
http://portforward.com/english/routers/port_forwarding/SMC/SMCD3G-CCR/defaultgui de.htm
The following are the important bits.
1. DynDNS client you will use.. Your standard router should offer sevices from several companies.. choose one and sign up.. And setup up the client in your main router. That is assuming you are not using a static Public IP which is far superior method.
2. The TC must have a static IP in the local lan.. so when you forward port 548 to it.. it doesn't get lost. The best way to do this is by using dhcp reservation in the main router.. (it is called other names.. but fixing IP to MAC address is available in just about any router). If you cannot do it this way tell me as it requires a different setup.
3. Decide if you will forward AFP directly.. or use a different port. I am not exactly sure why Tesserax is using 8888 but that is not required. It however does add a bit of security.. opening ports is always a risk.. opening them at some non-standard value can be helpful.
4. In bridge the TC has both AFP and SMB available.. but I strongly recommend against using SMB over internet. AFP is far more secure. Make sure you have a decent disk password on the TC as this becomes your main protection.
5. To remotely access is now easy.. albeit you must use a Mac computer.. type
afp://www.mydyndnsdomain.com
From FInder.. Go, Connect to server. (or into the address bar in safari does the same thing).
You only need to use the port like 8888 if you port translate.. which I think is very much optional.
But if you do just add a colon and the port at the end.
Anything unclear just ask.
