DHCP server and ethernet bridging

I maintain my sisters' mixed network remotely, and am having some problems with a no monitor, no keyboard wireless box with a webcam which is developing intermittent freezes.

I want to be able to look at it without tavelling 350 km.

They are a Windows house ( except for the stuff Ive added :wink: )

ie they have
CableModem -CAT5-> linux router (fw, dhcp,ssh) -CAT5->wireless AP -->webcam,laptops etc
-->desktops

I was thinking of getting them to plug a CAT5 cable in the box (currently with gentoo on it) with and connecting it to a liveCD linux on the laptop.

I *think* I want a linux live CD which will have a DHCP server at startup (to give an IP address to the wired connection on the linux box) and act as an SSH server.

A long length of CAT 5 cable across the hall lounge, sink and kitchen table from the router is not a solution.

I want to ssh to the router then the wireless connection to the live CD laptop then the wired connection to the webcam box and try and see whats happening.

An alternative would be some sort of ethernet bridge I suppose. How do I do that with a live CD that my little sister can just put into her laptop, switch on , and walk away and leave the rest to me ?