MS Proxy Sever 2.0 and router/isdn

Hi,
We are using router to connect to the internet. So ip addresses for all users to whome we want to ginve access are entered into the router. I want to use my computer as a proxy server to give more users internet access. I am using Microsoft Proxy server 2.0, so who can i done this by using the same router with the same gateway and dns rather than dial up connection. Where i should specify that gateway and dns in proxy server.
Please help me as soon as possible.

thanks

Shafqat Hamid