One really simple method:
You already have a DHCP server set up, right? Well your DHCP server should be telling the local computers what DNS server to use. So change the settings of the DHCP server so that they specify your own IP address as the DNS server.
Then you just set up a DNS daemon on your computer. All DNS requests will go directly to your computer, and you can respond to these requests with any IP address you like.
There's countless ways of going about this, but I don't know what your end objective is.