Xserve, Bridging and sharing question

[Yuowin]

Hello, I have a Xserve with 3 nic cards in it. I have a connection coming in through ethernet, I want to be able to hard wire it into the xserve, and then hard wire back out into a switch w/ dhcp enabled to create a steelhead router, how can I do this w/ Bridging with MAC OsX Server 10.3, and make internet connectivity through the server.

Thanks in advanced.