for the sbg900:
1. access the web interface as usual - i believe it to be 192.168.100.1
2. Login. The default login is:
User: admin
Pass: motorola
3. Click the "Gateway" button on the left hand side.
4. Click on the "Port Forwarding" tab at the top of the page.
5. Click on "config" at the top of the page.
6. Fill in these values:
Template: Custom
Name: PBall2
Port Start: 27910
Port End: 27910
LAN IP Address: 0 by default
You will obviously need your own LAN IP to tell the router where to send these people. Just go to Start > Run > "cmd" > "ipconfig" - this will list all adapters and their basic information , including IP address. Record your IP address, then you are prepared to connect to your router. If you've done it before, this is a piece of cake. If not, you should have at least cracked open the manual to have learned the default password and how to access it!
Enable: Yes
7. Click "Add" and "Apply"